The episode opens with what appears to be an angry Tyrannosaurus Rex staring down a frightened adolescent boy. The next scene opens with Ray, a policeman, and a few other CSIs investigating the body of that same young man out in the prairie. Ray notices a bloody, white bag hanging from a tree and collects it for evidence. The investigators notice that the young man has no ID, and only has a pair of keys with a faded logo on one key chain piece. They also find that his body has pattern puncture wounds on it that are consistent with the bite from a large animal like "Godzilla."
Dr. Robins and Ray go over the body and the doctor informs Ray that the cause of death was not the bite marks but rather a jerking of the brain consistent with rapid deceleration like in a car accident or a harsh fall. The "teeth" would have had to be at least three inches long. Detective Hodges enters, tells the group that the "bag" Ray found was part of a design by an Australian-based company that made simulated muscle for a "Walking With the Dinosaurs" exhibit that features three-dimensional constructed dinosaurs, and begs Ray to come with him to check out the exhibit. Ray and the detective go to check the exhibit out.
Nick and Greg, meanwhile, head to another crime scene and meet Detective Reed. She explains to them that the gardener had spotted the dead man in the house and called the police. She informs them that his name is Phil Coler, he was an Investment Strategist, the gunshot wound to his head is consistent with a suicide, and that the man had no reason to commit suicide. Nick tells Detective Reed that the man's daughter, Whitney Coler, along with her friend, Rachael Beck, were murdered about five years prior, a suspect (Eli Holt) who had blood in his van was arrested for the killing, and that the bodies were never found. Reed notices divorce papers which state that the man's wife was named Sharon, Nick finds signs of a possible struggle, and Greg finds powder wounds suggestive of the fact that the gun was held a foot or two away from Phil's body as well as a brunette hair consistent with the color of hair that Phil's wife had. The three notice that Phil is not wearing the gold watch now that he wore in every picture in his room. Catherine sits down for an interrogation with Sharon Coler, in which Sharon states that she does not know what happened to Phil and that she had bought him the watch. Catherine points out that the watch was among the disputed possessions in the divorce papers. Sharon says that she and Phil had not spoken in months, the reason that she wanted a divorce was because Phil had been cheating on her with Rachael's mom, and that she had walked in on the pair six weeks prior to filing for divorce, the only excuse that Phil was able to offer being that shared grief drove them together. Meanwhile, Greg finds the gunshot wound to be consistent with having been fired from at least thirty-six inches away. The fact that Phil's arm was only thirty inches long makes this evidence grounds for a murder charge. Another detective enters and informs the two that the hair found in the house is a DNA match with Carly Beck, Rachael's mother. Detective Reed and Nick go to Carly's house, call her out, and, when no one answers, kick in the door. The two search the house, find not a trace of Carly, and eventually go into Rachael's bedroom. After finding a new package of photo paper on the bed and remarking that there are significantly few more things in Rachael's room than when he had previously been there, Nick looks under Rachael's bed and finds a photo of what appears to be Rachael's body in a purple sweater (even though there is no camera, printer, or computer in the room). However, Nick points out that the day the two girls vanished, Whitney was the one wearing purple and Rachael wore gray.
Ray and David finish their tour of the exhibit, meet the tour director, Carl Evans, and enlist his help in photographing and cataloguing the mouths of all of the dinosaurs. Ray finds human blood in the mouth of one of the dinosaurs, but when he informs Carl of this, the man sees it as impossible. The dinosaurs require three workers to operate properly and all of the equipment is always locked up after hours, though there is no overnight security. Henry, a forensics investigator calls and tells Ray that the lab has completed restoring the dead man's key chain and that his name was Brian Lister, he was a member of the WLVU Paleontology Program, and he was studying herbivorous dinosaurs. He also had a fiancé, who was another student in the program and the department plans to bring her in for questioning.
Catherine goes over the evidence with Nick and Greg. They discuss possible motives for Carly's possession of the picture and for the fight that presumably got Phil killed. Extortion is discussed as a possible motive. Catherine tells them that the largest question is whether or not Carly had a hand in the death of her daughter. Nick points out that Eli is already in prison for the murder of the two girls and Catherine explains that Carly obviously knew something about the murders that she didn't initially share. Nick doubts that idea because he dealt with Carly several years ago and she was hysterical over the fact that her daughter was missing. Dr. Robins enters with his analysis and concludes that, since the body has been decomposing in a hot, dry climate for nearly five years, the photo could have been taken at any time. Nick says that they need to talk to Eli Holt, but Brass informs Nick that Holt is in a coma from an attempted suicide days earlier. The warden didn't know what drove him to do it after all of those years. Brass is, however, able to provide Holt's communication reports, which show that Carly had been writing Holt a lot of letters begging him for information regarding her daughter, but that Holt had never responded. Greg is able to enhance a portion of the background of the picture of Whitney's body and locate it at an area behind one of five new real estate promotional billboards. He then isolates it to one billboard in a dry, rural area and he and Nick go to check it out. The two find the body and Dr. Robins analyzes it. He tells Nick that the cause of death was strangulation but that the killer also severed two of Whitney's fingers and part of a third one with what the wounds suggest is a bandsaw. Detective Reed re-interviews Eli's cousins and finds out that Eli's uncle Bill (who is now dead) possessed a shed that Eli used to visit often. Reed, Greg, and Nick go out to the shed and find a bloody bandsaw.
The two continue to look around and Nick remarks that every tool in the shed is ancient except one shovel that had a fiberglass handle, which he believes might have been used to bury Whitney. After Nick finds a handbag with the letter "R" on it, he surmises that the same man buried Rachael as well.
Ray interviews Brian's girlfriend, Jane Lewis, who says that her and Brian watched the dinosaur exhibit on a date and that the last time she saw him was when he walked her back to her dorm. She also says that her and Brian had planned out their lives together and were going to become traveling paleontologists. Ray, however, shows her a video that he pulled from surveillance at the exhibit which shows her making out with another boy who made advances on her while Brian when Brian left to go to the snack bar in a moment of queasiness upon seeing the T-rex. Jane says that she doesn't know or care who the boy was and that the only reason that she kissed him was because she was caught up in the moment of the majesty of the dinosaur.
Ray and David set up an experiment with a dinosaur head and a torso and find that the dinosaur alone could not have caused Brian's wounds because it only had twenty-two pounds of bite force, just enough to barely scratch the torso. Ray theorizes that, if Brian died from a brain jerk, maybe he fell from a great height and his stomach landed on the bottom teeth of the dinosaur, providing the extra force that buried the teeth further into Brian's body. Since Brian's back was scavenged, investigators would never know that Brian did not have any wounds on his back to back up the false theory that the dinosaur had bitten him. The blood on the front teeth was then planted to make it look as if Brian had died of a dinosaur bite. Ray and David then go back to the exhibit and look at the area where the dinosaurs were kept overnight. Ray uses a crane to look at the dinosaurs on mouth level and finds blue and yellow fibers from Brian's shirt in the mouth of one of the Brachiosaurus. When David asks how Brian would have gotten that high up, Ray answers that Brian could have sneaked back in and used the same service crane that he did. Though what made him fall that distance still remains undetermined.
Detective Reed enters Catherine's office and shows her Phil's watch, which a local pawnbroker said was sold to him by a woman who fit the profile of Carly Beck. Carly had also come in a week earlier and sold a box of other things out of her daughter's room. However, in addition to the watch, Carly had also sold a camera on the same day. She had tried to sell a computer printer as well, but the man refused. Reed says that she has already circulated a report to used car dealers and is trying to find out if Carly is trying to unload the printer anywhere. Catherine examines the camera and finds the memory stick gone. She surmises that Carly must have been trying to get rid of all incriminating evidence by raiding Rachael's room and selling everything.
Nick tells Catherine that blood found on the floor of the shed and on the bandsaw match both girls and then Catherine tells Nick that she was just informed that a car dealership bought Carly's car and that Carly had left on foot. Detective Reed takes a police detail and they catch up with and apprehend Carly. Brass and Nick then interrogate her. Carly swears that she didn't kill Phil and says that she had recently been contacted by Eli Holt, who said that he now remembered where he had buried the bodies. He would give the maps to her for five thousand dollars each and that if she called the police, he would never talk to her again. She pawned all of the things out of her daughter's room for the first five, but it had led her Whitney's body, not Rachael's. She took a picture of Whitney's body and then told Phil about the two bodies and the deal that she had been given. She then asked him if she could borrow five thousand dollars. Phil had at first believed it to be a scam, but when she showed him the picture of Whitney's body, Phil gave her his watch to pawn for the money. He also told her that he could no longer keep living like this and that they both needed to move on. When she arrived home she got a phone call from a friend of Eli which confirmed that even though the first map had been wrong, she would still have to pay another five thousand to get the second one. She had then dropped the picture of Whitney on the floor in shock and despair. Carly begs Nick and Brass to make Holt tell her where the second body is and Nick asks her when she got the first map. She says that it was three days ago. Brass tells her that Holt has been in a coma for ten days. She then ponders whom she has been talking to and who else could know where her daughter is.
Ray brings Jane back in and also the boy that she cheated on Brian with, Travis Kilbourne (whom he was able to track down via the credit card that he used to pay for admission). He then presents them with the evidence that he has collected: prairie dirt on Travis's car, blood in Travis' car, Jane's fingerprints on the Brachiosaurus controls, and the fact that Travis knew Jane well before the night that they were at the exhibit together, because both of them attend the same College Paleontology program with twelve other students. Ray demands answers from the pair and Travis eventually explains. He says that thee whole thing was an accident. Brian had convinced Jane and Travis to sneak back in with him afterwards so that he could take a picture with the Brachiosaurus. Jane had operated the crane but had accidentally knocked Brian out of it and onto the dinosaur teeth. He had lifted himself off of the teeth and then fallen the rest of the way to the ground. Travis had then grabbed the bag and used it to cover Brian's body. They drove him into the desert and buried him. They did not tell anyone because they didn't want to get into trouble, as they were technically trespassing when the incident occurred. Ray informs Travis that he had also found a burger wrapper with lipstick on it. Travis tells Ray that he stopped at burger place afterwards because Jane was starving. Ray inquires of Jane if she "accidentally" pushed Brian off of the crane or if she had simply decided that a future with him would not satisfy her. Jane responds by asking for a lawyer.
Nick tells Brass that, though the postage on the envelopes sent to Carly is consistent with the prison mail system, the postmark on the envelope did not come from the prison, meaning that the informant was avoiding prison screening. However, the handwriting on the letter is the same as Holt's. Nick also informs Brass of the possibility that Holt could have told someone else about the bodies, but Brass says that Holt wasn't much of a talker. Nick and Brass go through Holt's cell and Brass tells Nick that the biggest event of the day of Holt's suicide attempt was his trip to the canteen, during which he bought candy, a drink, and a notepad. Nick finds that three sheets are missing from the notepad and both express their lack of belief that Holt would buy a notepad on the day of his suicide. Brass tells Nick that this was especially unlikely because there was no suicide note. The two review the case again and find out that the first officer on the scene of the attempted suicide was Jason Richter. The CSIs go to his house and call him out. When he doesn't respond, they break in. Jason tries to flee, but he is brought down. Nick finds the second map burning in Jason's garbage can and puts the fire out.
Brass interrogates Jason and he explains everything. He had come upon Holt in his suicide attempt and found the three pages (two with maps to the bodies, and one with a note to Ms. Beck explaining why he was sending her the maps and responding to her many pleas). He had at first thought that they might lead to buried treasure, so he waited for Holt to "die" and then he called the suicide in. When he realized that the maps led to the children, he decided to sell them and still get some money. When the first one didn't lead to Carly's child and she asked for the second one over the phone, mentioning Phil's name, he knew that she wouldn't call the police for fear of losing her daughter. He could not, however, be sure about Phil. So he killed Phil and staged the death to be a suicide. When he realized the game was up, he burned the other map and tried to run. However, he had not gotten rid of the shirt he was wearing the day he killed Phil and it still has his blood on it, pacing the murder weapon in his hand. Brass arrests Jason for Phil's murder.
Greg is able to use his talent for reading maps to locate the area where Carly's daughter is buried. Nick goes to Carly's house to inform her of this development and is met by a hug from a relieved and ecstatic Carly.