The show fades in to a woman in bed and covered in sheets and who appears to be dead until she blinks and sighs. She stands up, revealing a man beside her sound asleep. She wears a robe and walks around the bed, wakes up the man, rudely throws quite a couple of bills on his chest, and tells him that he could leave now. As the man gets up, she walks to the window to draw the curtains, and exclaims "That's unbelievable!"
Through the window, a man is seen climbing up the next building without any safety ropes. He pauses and looks down at the traffic below him before we are shown exactly how high the building he's climbing really is and how far he has to go to reach the top. Then the woman in the robe quickly grabs the phone and dials a number, anxiously waiting for someone to take the call.
The climber continues his stunt and onlookers start to gather below him. A bald man in one of the rooms in the building watches in awe. A couple is seen in a compromising position, and the woman just smiles as the climber passes their window. The crowd screams as the climber lets go and plunges to his death with a loud splat, and his brain is seen falling onto the people.
Stuck in traffic at East 35th St., Detective Mac Taylor tells Dr. Sheldon Hawkes to grab his case and they start walking. Hawkes tells him it's his third crime scene this morning and that he hasn't moved at this pace since his residency and asks if this is normal. Mac observes that Hawkes is missing the ME life to which Hawkes "sort of" agrees, and wonders how long the "rookie" status usually lasts.
Detective Don Flack is seen talking to a man with a video camera. Hawkes and Mac weave through the crowd and are met by Detective Stella Bonasera holding a container with a piece of the climber's brain. She tells them that the climber landed on the sixth floor terrace, and Mac notes that the climber was "high enough to reach a terminal velocity, the impact to the fall knocked the brain right out of his skull." Hawkes tells them that at least 50% of the man's brain is still missing, and Flack says that he found a shoe with about 10% and that they were still trying to search for it, but Hawkes tells them that there's no way they would find it with the crowd and the heat. Stella then gets a call and leaves for the next crime scene as Hawkes, Mac and Flack start to process.
Up on the sixth floor terrace, Flack and Mac examine the body. Flack sees blood stains on the balcony and figures that the climber hit his head there and his brain popped out and fell to the ground. He also identifies the victim as Paul Gessner, who had already climbed buildings in Chicago and New York. Flack also says that a buddy of Paul's videotaped the climb, and claims that Paul was "too careful and too good to just fall". Mac looks closer at the body and takes a broken cellphone from the victim's hand. Flack then says that the victim always called his daughter when he reached the top of the building. Mac notes that the victim wasn't even close to reaching the top, and then takes a sample of the resin powder which the victim used to keep his hands from sweating from the climb. As he goes on with the processing, Mac notices an abrasion on the victim's cheek, the hands were void of scratches and bruises, and that there's nothing under the fingernails to suggest the victim was struggling to hold on. Flack starts to think it's a suicide, but that scenario is promptly thrown out the window when he and Mac see the numbers "911" on the cellphone's broken display.
Shortly, Mac is seen in a scaffold going up the side of the building and checking for traces of resin powder to determine how far the victim managed to climb up before falling. He also notices the people from the next building watching him through their windows. Back to the body, Hawkes takes out a wallet from the victim's pants and takes out a picture of a little girl. Much later, Mac sees a small amount of blood on one of the window sills and connects it to the scratch on the victim's cheek. He looks up to check for the powder, and when he finds none he concludes that "this is where he stopped." He looks closer at the glass window and finds hand prints indicating that the victim was banging at the window with a fist. He then calls Hawkes and tells him to meet at the 34th floor.
Later, they find themselves standing inside a conference room, speculating on what made the victim pound on the window. Hawkes thinks that maybe the victim wanted to stop the climb, but if someone was in the room they could've easily let him in. Mac walks around the table and whips out a flashlight, looking closer at one of the chairs. He sees high velocity blood spatters and disagrees with Hawkes. They start processing, dusting out a handprint on the table and finding a used pregnancy test kit in the trash bin which tested postive. Mac also finds a pen with the words "Dandridge Hotel" written on it.
In another part of New York, Detective Danny Messer arrives at a scene where a man wearing a rhinestone bra is found dead. Detective Aiden Burn is already there taking pictures, and Danny tries to have a "little educated conversation." Aiden finds traces of mud that aren't from the victim's shoe just as Stella arrives. The three don't find signs that the victim struggled with his attacker, but his pockets were turned out and they didn't find his wallet which suggests that he was robbed. They debate whether he was killed then robbed or robbed then killed, and when Stella asks for an identification they find out that the victim is actually Whitman Price, a famous jeweller who recently designed a diamond bra worth over 8 million dollars. The identity is further confirmed when Stella's scan shows the bra to be real diamonds. Now the question is, "Why would somebody rob the guy and not take a million-dollar bra?"
We cut to Danny interviewing Nicole Jordan, a model who did a photoshoot wearing the diamond bra for Whitman Price's company the day before the victim was found. Danny asks her if she noticed anything strange about the victim, and she replies that Price left alone after the photoshoot, which was odd because she claims he always travelled with security. Danny then asks if Nicole had security, and she says the company provided her with a bodyguard. "Where I go, he goes." She says the company sees her as a commodity and they have to protect their investment if they want the money to keep pouring in. Before Nicole goes back to work, Danny asks if she knew anyone who would want to kill Price, and she answers "I don't know anyone who wouldn't."
At the Medical Examiner's office, Stella walks in just as Dr. Evan Zao is performing the autopsy on Price. Zao shows Stella a CT-Scan of the body and they find something embedded on the victim's esophagus, and he tells her that whatever it was, it cut through the esophagus and the right ventricle of the heart when the victim was hit in the chest and caused massive internal bleeding. Death was immediate that's why there weren't any bruises, but Zao tells Stella that there may be bruising on the inner dermal layers of the skin and whoever hit the victim was sure to have left an imprint. Zao then hands a pair of gloves to Stella, and he continues the autopsy. He reaches into the chest cavity and fishes out a huge diamond, which he hands over to Stella.
Back to Mac's case, Hawkes sees a mosquito "taking it easy" on the conference table. Since mosquitoes usually don't fly as high as a building's 34th floor, he figures that it must've been transported this morning by someone. Mac finds gunshot residue behind one of the chairs, and suspects that the climber may have witnessed a shooting, which would explain the attempted 911 call. Hawkes wonders where the shooting victim is, and they find what looks like drag marks on the floor leading outside the conference room to a door. They open it and a body with a gun shot wound to the temple falls out. Hawkes looks for a wallet and identifies the body as Lee Dillard, a senior partner of the firm where the shooting occurred. Mac sees a mosquito bite on the victim's neck, and he and Hawkes go back to the firm's conference room and trap their only living witness inside a container.
As Lee Dillard's body is put in a body bag, a man asks Mac and Hawkes how his law firm is involved in the climber's death. He introduces himself as Eli Bishop, a senior partner of the Bishop & Dillard Law Firm. Mac tells him that his partner was murdered in their conference room just as the body bag passes by, and Bishop stares in shock. Bishop tells them the last time he saw his partner was yesterday afternoon and that he got to work a this morning a little after 7am. Hawkes asks about how he hurt his hand, and Bishop says he got it from a sailing accident. The lawyer then excuses himself to make some phone calls and talk to his staff, leaving the CSIs a little suspicious.
Back at the lab, Mac steps out of the elevator just as Stella is passing by with a box in her arms. He offers to help her but she declines, saying that she can handle it. She then asks about Mac catching mosquitos, he tells her that it's their only witness because it bit the victim and there was a chance it bit the shooter. Stella notices Mac's reference to the insect as a "she", and he tells her that only the females bite. As he opens the door for her, they talk about how Hawkes is "a walking encyclopedia of tidbit information". Stella says that was better than Google. She asks if Mac has tortured him yet. Mac replies that it was "testing", and that all rookies go through the same process. When Stella asks where Hawkes is, Mac tells her that he's doing a little mosquito autopsy.
Hawkes and Aiden are shown simultaneously working their cases. We see Hawkes plucking a wing from the mosquito and extracting the blood from its abdomen. Aiden is making an agar (a gelatinous substance normally used for culturing bacteria and often placed in a petri dish) culture from the mud found from her case.
Meanwhile, Danny is working on the diamond bra and scanning for prints. Stella walks in with the diamond they got from the victim's throat. Aiden walks over to them and comments about how she's been "processing dirt all day while you've been shopping at Tiffany's". Stella tells them that the diamond was what the thief was after, and when the other lab guy Zack asks why the thief didn't take the bra, Danny says the diamonds embedded in it were laser inscribed and too small to cut. The big diamond, however, can be cut and sold in smaller pieces.
Aiden's cellphone rings, then her mood changes into that of urgency and she excuses herself, leaving Zack to take care of the bacterial colonies she was doing. Zack tells her it's not his field of expertise but she ignores him and runs off. Stella and Danny watch her go, then they get a hit on the prints they found on the bra. It belongs to a Fred Becker who was a professional jewelry thief now working as security in the jewel district. Danny and Stella start to leave to go talk to Becker when Zack calls their attention to the big diamond which is somehow having a weird reaction to the UV light. He asks if a diamond is supposed to react like that, and Danny and Stella say no.
Next we see Mac questioning Lee Dillard's assistant Adam Sorenson, who claims he had not seen his boss the morning of the murder. Mac shows him the Dandridge Hotel pen he found and asks if it is his, Sorenson scratches his arm and tells Mac that it could be his pen since he always stays at that hotel when he has to work late. Mac then asks if he was sure he hadn't seen his boss, Adam reassures him and tells him that he should probably talk to Eli Bishop. He tells Mac that Bishop had planned to split the partnership and that everyone knew about it except the victim. Mac agrees that it could be a good motive, then presses Sorenson about the pen. The assistant then admits that it's his, and that the victim had the habit of taking things from his desk. Mac asks when he last saw his boss, Sorenson says "Yesterday".
At the New York's jewel district, Danny and Stella are walking with Fred Becker, who tells them that he was the one who told the victim to wear the bra because it was the safest way to carry something that expensive around. Stella notes that he worked specifically for the victim's diamond company and that as an ex-jewelry thief might have given in to temptation. Becker tells them that he would never steal from the victim, but admits to being distracted at one photoshoot where he hit on women and the victim left him behind. Stella asks if anybody else knew where the bra was hidden, and Nicole Jordan's name comes up. Stella then tells Becker that the diamond they recovered is a fake, and asks him why would the victim go through the trouble of swallowing something synthetic.
That night, Hawkes runs into Stella who asks him how he is doing. He tells her that he feels like Mac is always looking over his shoulder, to which Stella answers it is okay as long as Hawkes doesn't look back. She also gives him advice on how to "impress" Mac.
Next we see Aiden talking to Regina Bowen in a cafe. Regina tells Aiden that she had been raped again by DJ Pratt, the same man who had raped her months ago. She says she didn't see his face but he "smelled" the same - paint thinner. Aiden asks for the clothes she was wearing that night for processing, and tells Regina that she will be there for her all the way like she did the last time.
At the ME's office, Flack and Hawkes talk to Mrs. Dillard after she identified her husband's body. Flack asks what time the victim left home to go to work, and Mrs. Dillard tells them that she and the victim were having marital problems that's why she was staying at her sister's place. She tells them she was jogging at the park that morning alone and off the main path. Flack asks if she loved her husband, and she tells him that nobody loved the victim except the first wife Connie. The only person she could think of who hated the victim enough to kill him was his partner. Hawkes asks when was the last time she saw her husband, and she told them it was two weeks ago. Hawkes thanks her and takes the glass, with full and clear prints, from her and takes it to the lab.
While Hawkes is processing the prints from the glass, he looks over at Mac who is busy with the pregnancy test kit. Later, Mac is having trouble with the soda machine and starts hitting it when Hawkes comes in with his theories. He tells Mac that all three suspects are lying, and puts his money on the partner, Eli Bishop, because he told them that he wasn't in the conference room, but they found his handprint on the table. Mac tells him that Bishop's alibi checks out, and that's when we find out that the couple making out while the climber passed by their window were Bishop and his secretary. Hawkes then puts it on Adam Sorenson, who admitted that the pen was his, but Mac tells him that Sorenson's story is plausible, that the victim may have taken the pen. Hawkes doesn't think the wife did it, but Mac tells him that the prints on the glass match the ones on the pregnancy test, which means that she lied about when she last saw the victim. They walk to Mac's office, where Hawkes shows him that the blood from the mosquito belonged to the vic and another male, and that scratches the wife off the suspects list. Hawkes doesn't doubt that Bishop or Sorenson will not give a DNA sample willingly, so they decide to go back to the conference table and swab the handprint which is sure to have epithelial cells. Mac then decides to go back to the mosquito.
Cut to Mac in the lab. He takes a closer look at the mosquito's wing and finds traces of gunshot residue (GSR). In another part of the lab, Aiden is processing Regina's photos and clothes from the night she was raped the second time. She doesn't find any fibers or hairs on the clothes and starts to get frustrated. Mac comes in and Aiden asks if she could be reassigned, but before she can finish, Mac tells her that it is already done and to make sure that they get the suspect this time.
Back to the diamond case, Zack shows Aiden's bacterial colonies to Danny and Stella and tells them that the soil from where the bacteria came from is consistent to those at Central Park. Danny remembers Nicole Jordan to be at Central Park, but Stella thinks that the model is too skinny to kill the jeweler. Danny then remembers Nicole's bodyguard, whom the model says goes wherever she goes.
Danny and Stella go to one of Nicole Jordan's ("Christmas in the summer") photoshoote on the rooftop of a building. Danny comments on the heat, Stella asks why he's wearing a jacket, he says his mother still dresses him. As they approach, Nicole's bodyguard spots them and makes a run for it. Stella calls for backup while Danny goes after him, and after a lengthy rooftop pursuit finally tackles the guy and puts him in cuffs.
We see Aiden coming up behind DJ Pratt, her rape suspect, and introduce herself. He tells her he knows who she is, and mocks her when she asks of his whereabouts three nights ago. As Pratt dips his paint brush on paint thinner, a short flashback is shown of Regina and Aiden's conversation at the cafe, telling Aiden about the paint thinner. Aiden tries to convince Pratt to cooperate but he blows her off. She sees the ring on his finger, which has the exact same design as the bruise on Regina's cheek. Pratt asks her mockingly what crime he committed, Aiden tells him he knows exactly what he did and that she knows he did it before walking away.
Cut to the ME's office. Dr. Zao is taking pictures of Whitman Price while Danny and Stella watch. He then shows them pictures of the bodyguard's fist and the subdermal bruising on the victim's chest, and they conclude it's a match. Apparently, the victim had just swallowed the fake diamond when the bodyguard caught up with him. The bodyguard searched the bra and when he didn't find the diamond he asked the victim where it was. The victim mocked him, saying that he'd have to take it "over my dead body", and that was when the bodyguard hit him in the chest. The victim trashed around, gasping for air and knocking over some garbage cans before falling near the steps, dead. Stella confirms that they've got the killer, but the real diamond is still missing.
Later we see Stella looking at Nicole Jordan's pictures in her office just as Aiden walks in and asks if she has a minute. Stella asks what's on her mind, and Aiden asks for advice on how to "tell someone who's raped a second time by the same guy that he's gonna go free again". DJ Pratt was acquitted 18 months ago because Regina refused to testify, and now that he's struck again, Regina's expecting Aiden to catch him "based on paint thinner and gut instinct". Stella tells her that if Aiden believes that Pratt is guilty, she could keep trying. She tells Aiden that as scientists, they could analyze the evidence and determine whether a person is guilty or not, but they can't always come to the rescue. Aiden wants Regina's torment to end, but she feels so powerless. Stella says "There's always that one case that haunts us and strings us along", but once you close it, it's all worth it no matter how long it takes. She assures Aiden, and she suddenly gets excited when she realizes "it's there" and leaves Aiden slightly comforted but still unsure.
At the photoshoot after party, Stella and Danny confront Nicole Jordan about stealing the real diamond. Nicole doesn't know what they're talking about, but Stella tells her what they know. Nicole had switched the real diamond and the fake diamond in her dressing room where she was sure to be alone, then hung the real one in the Christmas tree as a decor. Danny tells her that he couldn't figure out how nobody knew it was a fake, not even the victim, and her plan would've been flawless if her bodyguard didn't kill price over a fake diamond. Stella whips out a small UV light, and as she flashes the light on the tree tells Nicole how fascinating the device is because it can detect blood, semen, saliva... "and in this case, a real diamond." Stella takes the real diamond (the one that doesn't glow fluorescent) off the tree and gives it to Danny, who puts it in an evidence bag. Stella tells Nicole that she "hid it in plain sight" and left it on the tree so in case the fake is discovered, they won't be able to trace the real one back to her. Nicole tells Stella they can't prove anything, but Stella says they will once they dust the diamond for prints. Danny comments on how wrong some people are about models (all beauty and no brains) before cuffing Nicole and leading her out of the party. Case solved.
Mac and Hawkes still haven't figured theirs out, and we see Mac walking to his office with Hawkes while telling him about the GSR on the mosquito's wing. He thinks that it bit the shooter as he was firing the gun. Hawkes confirms that the unknown male blood in the mosquito was not Bishop's, and they zone in on Sorenson. Mac then recalls that Sorenson wasn't just nervous but he was also constantly scratching various parts of his body while they were talking. But as much as they want to move, they can't figure out the motive.
They check the video tape of the climb the climber's friend took, and upon closer examination they see the flash from the muzzle of the gun because the blinds were open. They go back to the conference room, and Mac tells Hawkes that while he was up on the scaffold there were a lot of people watching him from the next building. Hawkes wonders why would a person shoot someone and not close the blinds, then Mac tells him so that someone else could watch the murder.
Much later, Mac is at a room in Dandridge Hotel, looking through the window to the other building. He notes that the room has a perfect view of the conference room and looks at Connie, Dillard's ex-wife and the woman seen in bed at the start of the show. Sorenson is also in the room, and so is Hawkes. Connie tells Mac that she had just arrived that morning and she was there for the victim's funeral, nothing more. Mac disagrees, saying that she had come here two days ago to watch Sorenson kill her ex-husband, and that Sorenson was there right now to "close the deal". Mac walks closer to Connie and asks if he was right, and the woman confirms him by sitting on the bed. She says that she did it because Dillard divorced her for a younger woman. Although she signed for a pre-nuptial agreement, she says it didn't change the fact that the victim wouldn't be where he was without her. What really pissed her off was the new wife got all the benefits, along with Connie's money.
Mac then shifts his attention to Sorenson, saying that he took advantage of her anger to gain a little cash. Sorenson still denies his involvement. Mac asks what was in the bag he was carrying and he says it's his gym clothes, but when Hawkes takes it he finds wads and wads of dollars - Sorenson's cut. The room is in Sorenson's name.
Sorenson calls Lee Dillard a bastard who treated him like a slave. He was happy to shoot him. Mac tells them they could've gotten away with it if it weren't for the climber, who happened to see the shooting. Sorenson had no way of getting the body out of the building because of the cops who were there for the climber, and Connie was afraid the climber might be a witness so she called Sorenson using the phone in the room. It was that phone call that helped them crack the case. "That, and a mosquito."
Finally we see Aiden asking for the evidence box on Regina's first rape. As she re-examines the evidence, she can hear Stella, Mac and Regina's voice, all from previous conversations. Then she takes Pratt's hair sample from the evidence box, lays it on the table, and looks around before taking a cutter and breaking the seal. She takes the single hair out and takes the old panties, looking very nervous and very unsure of what she's doing, leaving us wondering about the decision she will make.