Mac is on the scene of a shooting. A gun is on the floor pile of blood, a guy dead on the bed. The vic is Jay Knight. Danny is also there, and he picks up the gun and hands it to Mac, who seems to sniff it. Danny sees some high velocity blood spatter and heads to sweep the rest of the apartment. As he does so a suspect slams out of a closet knocking on the ground. He runs out the building in the street, and Danny is chasing him, blood on his face. Cops are running behind, The suspect heads down the subway, Danny on his trail. He hides behind a column. There are shots fired, they run. Danny shoots down the suspect, and Danny hands him his gun. Mac and the two other officers arrive; the downed guy was an undercover cop. It looks like the guy who ran out, but Danny isn't sure anymore.
EMTs are on the scene of the subway. Flack informs Mac that the cop was Detective Rodney Minhas. There are eye witnesses that saw the whole thing, and there stories are consistent: "A guy came down the south stairs, ran to the middle of the platform and hid behind the column. He sees Danny come down following him, and fires at Danny twice. At this point they start diving for cover. Then officer Minhas comes down the north stairs, and starts shooting at the same guy Danny was chasing. There are three people down here shooting." Some cops are talking about it, and insult Danny. Danny defends himself and Flack tells the officer who mouthed off to Danny to get out of here, that he doesn't want people to make their minds on something until they get all the facts. Danny tells what he remembers, he is shaken. He can't be sure if both his shots hit the victim or not. IAB is down there already, Mac informs him they will want a statement and that he shouldn't say anything until they give a prelim report. Aiden is on the scene, she found a cell phone of a guy who was standing right next to Danny when the firing started. It's a message recorder. An IAB officer, the one from last episode with Stella, comes and informs Mac he is going to get a statement, but Mac insists Danny goes to the hospital first.
Stella is on the scene of a girl dead in a restroom. The girl is Sandra Lopez. A cop comes up to her; she was only 19 years old. It was her friends that called 911, they were all nannies. She worked for the Mayeson's who are the biggest antique importers in the city. One of the nannies has to go, the baby she is taking care of needs to be taken home. Stella learns that the Mayeson's baby, Daniella, has been taken in to welfare services until the parents come to get her. Stella checks her out to see if there is anything up with her, she UV's her to check for bruising, and takes a picture of Daniella (who is adorable and seems to have captured Stella's heart).
Mac is with Hawkes who tells him of the wounds on the cop. There was a round in the shoulder, and the other wound was on the body. There is no way to tell who fired the fatal shot. Mac heads to a sound tech that uses the recorder to figure out what happened. There was a shout from Minhas, stating he was undercover.
Stella heads to Hawkes, who informs her the nanny died from blunt force trauma to the head- one blow. The murder weapon was a rock with a v shaped edge. There was also burn trauma in her nose and an edema on her throat, and she was sexually assaulted. Stella and some other csi's head out to the park looking for rocks, in the rain.
Stella is back at the lab checking out the rocks she collected and spraying them. She finds one with a thumbprint, but she gets no matches off of it.
Mac is with Aiden looking at a floor plan of the subway and the attack. They are going to account for the bullets. The one that killed the cop was a through and through but they have to figure out which which gun the missing bullet was fired from: Danny's, or the perp's.
Danny is at the hospital, and the nurse claims he won't be much longer. Danny is distraught; he wants to get back to work. He gets his coat on and heads to leave. The doctor arrives and Danny tells him that his friend said to wait, he went to the bathroom, and he'll be right back, and heads out the door.
Stella is questioning the butler, who claims that the nanny got along with the owners, Daniella's parents, for the most part. Unfortunately the parents are away on a business trip. He claims that a prized nesting doll was stolen, but was mysteriously returned so the police were never involved. When stella asks if the nanny had any enemies, the butler suggested one of her guy friends, who had come off as a bit edgy.
Stella heads to a club with a flame breather and devils dancing on the bar. The bartender is Steve Dark; she shows the badge and pulls him aside. She asks him about Sandra Lopez, and he says that there are tons of women around this bar, and they start to look like ham sandwiches. Stella informs him of Sandra's death and that she had been raped within the last day or so, and he admits she came on to him. She tried to breathe the fire, but couldn't. Stella gets prints from him but he's not a match to the rock.
At the subway station, Mac gets Aiden to head to the station with Flack. Danny arrives, and he is upset, Mac informs him that his story has not been supported by the eye witness's recording device. Mac thinks that the bullet missing from Danny is the one that hit the officer. He hands Danny a card for a lawyer. Danny tries to argue with Mac but soon heads off.
On the platform, Flack is going over it all again with Aiden, and they check every surface for the two missing rounds. Aiden finds a bullet skid mark, and by following the direction of the skid, she finds the bullet lodged in the steps. She tweezes it out and checks for blood but finds none. She is going to check to see if its Danny's missing bullet.
Mac and Aiden are with the ballistics tech, who shows them that the bullet Aiden just found matches the bullet from the DOA at the apartment. The guy Danny was chasing, was killed by the officer, meaning that Danny's missing second bullet is the one that killed Officer Minhas.
Danny is sitting at a desk and Flack comes in, asking how he's doing. Danny is sick to his stomach, upset at killing the officer. He doesn't want to call the lawyer. Flack tells Danny that he and Aiden are going to go the apartment to check things out there. Danny admits he feels very alone in this, as though Mac is only worried about the reputation of the lab, and that Mac doesn't have his back. Flack tries to assure Danny otherwise, telling Danny that he needs to believe in the system but Danny confesses that he can't and leaves.
Stella and Flack check out their nanny again. They want to run her prints in the system because something about her doesn't feel right. They get a hit and learn that the nanny was a thief whose print popped up in an open theft case giving Stella an address. Stella heads to the address, and one of the friends, Glenda Wallace, is there. The necklace was from her employer's home. A 10 karat blue sapphire necklace was stolen. She asserts that Sandra wasn't involved, and then she remembers that they were "playing dress up." Stella doesn't believe her, so she gets Glenda's prints.
Aiden and Flack are at the DOA's apartment. The blood splatter found before, doesn't match the blood of the DOA. They don't think it was the guy who ran because he would have been bleeding heavily and there was no sign of that. This means there were three men in this room. There is a flash. The perp and Knight shoots. Knight's bullet hit the third guy as the perp shot at Knight. The bullet from Knight goes out the open window and into the tree across the street.
Mac is with Hawkes and the portion of the tree. Hawkes splits the tree to get to the bullet. Hawkes manages to get the bullet out, which Mac compliments him on. Hawkes informs him he wanted to be a sculptor.
Glenda never touched the necklace that Sandra apparently lifted. But Stella wants to run her prints through A.P.H.I.S. It comes up with a match to another robbery, a Rolex, at the other friend's employer's address. They get her prints, and she asks for a lawyer, saying that that's what the embassy told her to do if she ever got into trouble.
Mac is with the ballistics lab tech who says that the bullet from the tree matches Knight's gun. The blood sample from the bullet in the tree matches the blood sample from the splatter in the apartment, and they both match the undercover cop. He was shot there, so it couldn't have been Danny who killed him.
Aiden and Flack are trying to figure out how he got to the subway without leaving a blood trail, but Aiden remembers that there is another subway entrance. They head for the other entrance down the block where they find a car parked on the side of the street with a full days worth of parking tickets stuck in the wipers and blood on the sidewalk next to it as well as a bloody towel hidden in the wheel well. Minhas was standing in front of teh passenger side door waiting to get in but he couldn't because the driver and the keys were in the apartment.
Danny is being questioned by the IAB. Danny says he did everything according to procedure and explains what happened, saying that he didn't know that Minhas was a police officer. He admits he just wanted to say his piece on the record. The IAB detective is agressive and says that the suspect didn't fire till Danny started a confrontation which can't be true because Danny only fired two shots. The IAB officer leaves. Outside, Mac meets Danny and, angry at him for talking to IAB, informs Danny that his findings show that he didn't kill Minhas, and now Danny could have screwed himself as his statement could contradict everything they determined. Mac walks off, saying that the information is now useless when it comes to exonerating Danny.
Stella is with Chad again, examining the nesting doll. She takes it apart, checking for prints on each piece, using the fumer. She finds one on a smaller piece, and runs it but it matches none of the prints they had in file. That means there is only one name left, Matrice Singh, the third friend who wouldn't give her fingerprints. Stella is in interrogation with her and her lawyer, saying how they have her. The print at the Myerson's matched the rock that killed Sandra and the print is hers. Stella discusses the ring, how one nanny steals from the second nanny's house, the second nanny steals from the third nanny's house, and the third nanny steals from the first nanny's house. The lawyer tried to stop Stella, but Stella says "let me finish." None of the girls are in the system, so the prints come up as ghosts. Despite what the lawyer says Matrice confesses to it. She says the plan was to pawn the items and split them three ways. That that's why the prints were wiped down (except the smallest nesting doll which Matrice found particularly cute. She tells of how she confronted Sandra when Sandra got cold feet and placed the nesting doll back. She says she did it because she wanted health insurance because if you get sick, you need to pay for it. She was tired of it.
Mac and Stella discuss her case, he says its done, asking her why she is so upset. But Stella claims the real crime is in the families. The family Sandra worked for waited 2 days to pick up their baby. The baby has everything she could want except her parents. She is upset about all of it. He comforts her, telling her that she is the strongest person he knows and if the kid needs anyone right now it's her.
Mac is questioning a Michael Armstrong. Mac shows him all the evidence. Michael claims he wasn't involved in any of the shootings. He says Minhas was his partner. They were going to shake down Knight. He claims that Rodney Minhas dated his sister, that Minhas wasn't there to try and kill him, but Mac tells him he's wrong and he leaves
Danny is talking to Mac, saying that the DA won't prosecute. IAB was called off and it won't be a problem. Mac lectures him saying IAB is saying it's a pass not exoneration. He says if something happens like this again, it's going to come up. Mac feels the need to tell Danny something, one that he thought he'd never have to say. One is that he was strongly discouraged from hiring him, but he followed his gut and the last five years he showed he did right. Then they said that the decision was his to hire him, and that eventually he'd realize his mistake. Danny says he didn't make a mistake. But Mac says Danny shot wild. The shot could have gone anywhere. He says the story of him turning didn't happen though Danny swears it happened. He says he couldn't have possibly have seen him until he started running at him. He gives Danny his gun back and tells him he's off the promotion grid and that he should pick it up and takes it. He gets a call and says hold on, and looks at Danny to leave. Danny gets up dejected. He gets the call put through, from the chief.
Stella is with Daniella playing with her. Stella hugs her and smiles at her. The parents have finally come, Stella looks upset. She's going to talk to the parents.