The scene opens with a girl being rushed into the hospital; her face badly injured to an extent that she cannot be easily identified. Megan walks in to check on the patient. The doctor informs her that there were two girls brought in; one of them is dead and one is in the intensive care unit. Megan comes out of the room, when Donna’s father walks up to her and asks her about Donna. Megan tells him that Donna couldn’t make it and she is dead. He also asks about Carrie; the girl who is coma. He wants to know whether she was drunk, as she was the one who was driving. Carrie’s father does not appreciate this and a brawl ensues between the two fathers. Megan calms them down by pouring water over them, from a vase kept nearby. She tells them that if they want answers; then they should try not killing each other.
She will give them the answers once she is done with the investigation. She tells Danny that he victim’s name is Donna. She meets Aiden; and their date is cancelled as she had an important work to do. Peter is examining the car. He is told that there was a beer bottle found in the side pocket of the driver’s seat. Megan is examining Donna’s body. She was ejected from her seat. Ethan tells her that there is an old mark on her foot. Bud and Sam tell Donna’s parents that Carrie; who was driving the car, was drunk and was speeding over the limit. Donna’s father blames Carrie and the mother wants her arrested. Kate comes in and announces that she found a bullet in Carrie’s body; but Megan is not surprised. She points out to a bullet wound on Donna’s body; and it showed that the path of the bullet was through and through.
The bullet had passed through Donna’s body and lodged itself in Carrie’s. Megan declares that this is murder. The doctor tells Sam and Bud that the bullet is lodged in Carrie’s heart; and that it will take them a few days to remove the bullet. But Carrie’s father is against this. He tells Bud that they can forget about getting the bullet; as the doctor has told him that Carrie would do just fine without the bullet being removed. Sam explains to him that he bullet is the best way they could track down the culprit. The investigative officer informs Sam and Bud that there is this car, on which there are traces of paint from Carrie’s mustang. But she also tells them this contact had happened prior to the accident. Moreover there is a gun found under the driver’s seat of this car. The car is registered under the name of Rob Martin. Megan calls Kate and Peter into the autopsy room and wants to reenact the accident.
They infer that Donna and Carrie were facing away from the gun, as Donna had seen the gun and both of them had instinctively turned away. But Peter tells them that there was no bullet shot on the door of the car; which means that the shot came through the open window. Peter goes to check on the car. Sam and Bud go and meet Rob martin at the hospital. Sam tells him that they know that the mustang had brushed his car before the accident and that they were drunk. Martin tells them that he did chase the girls but never touched his gun. Sam tells Bud that it is difficult to prove that Martin is the shooter; unless they get the bullet from Carrie’s heart. Peter tells Megan that the angle of the shot proves that the shot came from a truck or an SUV. They need to find out where the girls were before they got shot.
Ethan tells Peter and Megan that the white residue found on Donna’s pants was kryptonite. He educates them about the mineral that is found in Serbia. He tells them that though kryptonite does not actually exist; a mineral having a similar composition was recently found. He further tells them that Donna was geology major and that the museum had recently received a sample of this mineral. This proves that the Donna was at the museum before they got shot. Sam and Bud go to the museum. The people at the museum told them that Donna was there last night, and after some work she left. A while later Carrie came in looking for her. They also learn that there was a rivalry between a girl named Susie Foster and Donna; as they were vying for the same scholarship, when Donna finally won. Bud makes a note of it.
The lady from the museum also tells him that it was strange that even Carrie was staring at that picture. Curtis tells Megan that he had nominated her name for an award and she won. Lacey brings a picture for her mom as she had asked her for one for the office. Sam, Bud and Megan meet Susie. She tells them that she wasn’t a Donna fan; but that doesn’t mean she shot her. She tells them that she hated Donna for acting like a sick girl, as she had lupus. At the hospital, confirms that Donna had lupus. But she finds it strange that autopsy did not show any signs of that condition. Reality rams into her. She realizes that they had declared the wrong girl dead. The faces of the girls were severely bruised and hence they were misidentified. So now, Carrie is dead and Donna is the one who is alive. When Carrie’s parents are informed, they are furious and devastated.
Ethan finds traces of acetic acid on the actual Donna’s sleeve. Peter, Sam and Bud go to Carrie’s place and realize that the lace seemed too protected. Carrie was definitely afraid of someone. Peter tells Megan that Carrie had a stalker. The stalker would sometimes be in her room and roll on her bed. Carrie had informed the campus police. Megan and Aiden are at the award ceremony. They sneak out to spend some alone time together. Just then we see that Lacey has passed out in her room. Megan and Aiden reach the hospital. The doctor tells them that Lacey has diabetes. Bud tells Kate that Rob Martin is clear. So now they are still searching for the real culprit. They tell Kate about the acetic acid found on Donna’s sleeve which is used for developing photographs.
They analyze the picture from the museum. Next, Donna’s mom gives Megan a box that Carrie had given her for safe keeping. In the box Megan finds a strip that connects to Susie. Meanwhile, Ethan looks at the photograph from the museum and tells Peter that the guy in the photograph is the stalker. He knows that because he belongs to a group that develops their own photographs. Sam, Peter and Bud reach that guy’s place. They find Carrie’s pictures all over. They also find photographs of Donna’s room in the hospital. Bud tells them that the stalker does not know that it is Donna. He might think its Carrie and attack her. They rush to the hospital. Next at the hospital; Susie walks into Donna’s room with a syringe in her hands. Megan is waiting for her. Megan asks why she trying to kill Carrie.
Susie tells her that Carrie was supposed to be her best friend and not Donna’s. She hated it when they mocked her. And then she decides to kill Carrie. She tries to inject the syringe into Donna; but Megan stops her. There is a struggle between them. Just then Sam, Peter and Bud arrive and arrest Susie. Kate arranges for a meeting between both the parents, so that they can amend things. But someone has to take the fall for the identity mix up. It is Curtis and Kate is the chief again. Lacey is scared about the diabetes; but she knows that her mother will always be there for her. The episode ends.