Carrie arrives at the crime scene of a man who fell off of a building. It is unsure if he was pushed, fell or jumped. Carrie is surprised to find that she recognizes the man, Dr. Eugene Lustig. He is a neurologist who Carrie decided to help. She joined part of a research team that all had memory power similar to Carrie. Eugene is the reason that Carrie didn't crack up from thinking about all of her bad memories constantly.
Jay wonders if it could be a suicide but Carrie doesn't buy it since there is no suicide note. Carrie and Al investigate the area that Lustig fell from. Carrie finds clues that suggest the killer used a potted plant to knock Lustig out. Al thinks that maybe it is just a suicide but Carrie says he is the most positive person she knows. He was the one who gave her hope when she had none.
Back at the lab, Joanna tells Carrie about the top soil she found on his scalp and under his shirt. Joanne supports Carrie's thought that someone else forced Lustig over the balcony. Carrie has a flashback to when she first met Lustig.
Jay tells Al that the ex-wife is clean but after digging around the university he finds one professor with a grudge against Lustig. Alwyn Pierce, something of a protege to Lustig, was difficult to get along with and accused Lustig of rigging her tenure vote against her.
Al and Carrie visit the university to interview Alwyn. She gets aggressive when Carrie says that Lustig thought Alwyn had fraudulent research. When questioned about her whereabouts during the murder she says she was sleeping, and they can ask her cat for proof. She rushes away to teach a class.
Eliot Delson tells Al to ease up on Alwyn until they have some real proof. The university brings a lot of money to the city so they don't need the negative press. Jay reveals a security tape which shows Alwyn stealing a box from the neurology lab. Eliot tells Al to not worry about the search warrant and just go arrest Alwyn.
When Cherie and Al show up to Alwyn's apartment they find her dead body in a chair. There was no struggle and whoever was the murderer was let in by Alwyn. Carrie finds the box that Alwyn stole from Lustig's office. It's full of tapes from Lustig's study of Carrie. Carrie has a flashback of Lustig telling her how lucky she is to remember everything. She says that it is also a curse because she can't forget anything. He points out that the one thing she can't remember is the day her sister died. She is unable to remember because she had too much adrenaline in her.
Jay finds that in the days following Alwyn's burglary, she contacted three of the six memory study participants. The other three were unable to be reached. Carrie wants to know why she called. Al thinks if they can find what Alwyn was looking for on the tapes they can find the killer.
Al and Carrie meet up with one of the other study members, Dale. He was contacted by Alwyn about joining a follow up study, probably to make a name for herself. Dale wasn't interested though.
Cherie and Jay meet up with another study member Todd. He was in Norway at the time of the murder and had Alwyn's phone call the week before. He has no reason to hate Lustig or Alwyn, he's too busy making millions of dollars.
Carrie meets up with Ruth, another study participant. Ruth says that Alwyn asked her if Lustig ever asked her to lie. He of course didn't but she had to check because one of the group members told a huge lie. She points Carrie in the direction of their group session. Lustig wanted to see if they could influence each others recollections. Jay can't find a tape for that session. Carrie says whatever is on that tape is the reason Lustig and Alwyn were killed. She looks behind her and sees a car about to run her down and she jumps out of the way just in the nick of time.
While the police don't have the tape, they do have Carrie. She sits down with Al and a stenographer and recalls the meeting. The team has a long book of things to research to find the one lie. Carrie remembers a lot of art hanging in Alwyn's apartment. Dale was the one who talked about seeing a Vermeer painting. They find out that the painting was in Spain at the time so there is no way he would have seen it. Whatever he did that day he is willing to kill to keep it secret. Jay searches the database and finds that a university student was murdered that day and left in her car.
Carrie confronts Dale about the day that he said he went to an art gallery. He changes his story about what he said that day. He tells her to check the tape but it's gone. Carrie shows Dale the picture of the murdered girl but doesn't say much more than the fact that he audited them.
Jay has found that there are another 8 possible victims that were killed after being audited by Dale, therefore Dale may be the serial killer.
Carrie brings in Dale and questions him. She asks if he knows any of the murdered girls and he says he doesn't know them. Carrie remembers that Lustig said that sometimes an extreme amount of adrenaline can erase a memory, like what happened with her sister. Carrie believes that this is what happened to Dale's memories of murdering those girls. She tricks him into admitting that it was raining the day Lustig died but it was a sunny day. Carrie says she is the only one who understands him and asks how long he gets where he won't have memories. He says that sometimes he doesn't have memories for a few days. He explains how it started with him killing a cat. Killing people would give him brief periods of time from all of his memories.
After leaving the interrogation room Carrie has a flashback. She remembers Lustig saying that nothing brings you into the present like a task, and he suggests she get back into police work.