Henry's old boss, Captain Connors, and his daughter Trish come to the Psych Agency for help. Connors, who is suffering from early onset Alzheimer's, thinks he's solved a murder but he can't remember who's been killed or who the killer is. The police don't believe him so he asks Shawn to psychically look into his head for the answers. Since Connors was always great to him as a kid, Shawn agrees to take the case.
Shawn and Gus begin by retracing Connors' steps. They start at the coffeehouse where Connors was when he thinks he solved the crime. To Shawn's dismay, this is happens to be not only a regular haunt of Connors', but also of Henry's and all of his old cop buddies, who just happen to be there now.
Meanwhile, at the police station, a woman, Sabrina Vito, comes to Juliet for help. Her boyfriend, Mike McMillan, has gone missing. She's been unable to reach him and has been putting up flyers all over town.
Back at the coffeehouse, Shawn and Gus sit with Henry and Connors as they reminisce about the old days. Shawn notices a note Connors wrote to himself describing a white male, 20s, bald. He looks up and sees one of Sabrina's missing posters. Connors' description matches the picture of Mike perfectly. Shawn tells Connors he's getting a vibe that Connors was sitting at the same table when he saw the victim, Mike. This jogs Connors' memory, who tells them he saw Mike arguing with Mort Crocker, founder of Mort's Family Restaurant chain, who blamed the murder on a mountain lion. Shawn and Gus look confused but Henry reminds Connors about an old case of a woman named Zoe Sharp, who was killed by a mountain lion, but Connors always thought it was murder. It seems that Connors is mixing past with present.
At the Psych office, Gus shows Shawn a newspaper article about the death Mike McMillan - who was killed by a mountain lion. This must have been the murder Connors thinks he solved. Two mountain lion deaths in the same case can't be a coincidence. So Shawn stops by Henry's to get more information. Henry tells him that Zoe Sharp was Crocker's assistant and there was a rumor that they were having an affair. There wasn't any proof and Connors was always upset they couldn't nail Crocker for her death.
Shawn and Gus go to the Zoo to "talk" to Mike's killer, the mountain lion. They learn from the zoo director that the mountain lion who attacked Mike only did so because it was malnourished, which is strange because there was record rainfall this year so the lions had an abundance of foliage and prey to feed on.
Shawn and Gus go to the woods to check out where Mike's body was found. They discover through looking at the paw prints and drag marks, that Mike was murdered elsewhere and the mountain lion only fed on him after he was dead. The mountain lion, they conclude, was framed.
While out there they meet Ranger DeSoto who brings them back to his ranger station. There Shawn sees a picture of DeSoto with Mort Crocker and his wife Edna at a wildlife fundraiser. They also see a cage outside with blood on it, which makes Shawn remember that the mountain lion had a matching cut on it. They ask DeSoto how often mountain lions attack humans, and he tells them not often, but this has been a dry year this and the lion that killed Mike must have been hungry - the exact opposite of what the zoo director said.
Shawn and Gus go to the police station to tell them about the link between DeSoto, Crocker and the mountain lion. There they see Sabrina, who tells them that Mike was in town looking for his birth parents. His birth mother had been dead for almost 20 years but he had finally tracked down his father, who was a wealthy man and difficult to get to. Sabrina is holding a box of Mike's things, in which Shawn notices shoes with soil in the treads and a prescription for biotin.
Gus tells Shawn that a biotin deficiency can be hereditary, so they go to Crocker's house to confirm what they suspect - Mort Crocker was Mike's father. If they find biotin there, they can prove they're right. At the Crocker estate, they run into a roadblock by the name of Edna Crocker, so instead they track down Crocker's pharmacy and there they confirm that Crocker did in fact have a prescription for biotin.
They call Lassiter and Juliet and let them know that Zoe Sharp was Mike's mother, and that when Crocker found out, he probably wasn't happy about now having to share his fortune. Connors says Crocker killed Zoe and dumped the body, but it was a dry year that year and he got lucky, the lions were hungry and ate the evidence. Shawn and Gus say that this time, he didn't need luck. He had help in the form of Ranger DeSoto. Lassiter tells them that Crocker was in Chicago when Mike was killed. Connors, frustrated and out of control, doesn't believe him and goes after Crocker himself.
Shawn, Gus, Lassiter and Juliet follow Connors and Trish to the Crocker estate. They chase Connors as he runs into Edna's private greenhouse. Shawn notices potting soil there, the same soil that was on Mike's shoes. He realizes that it wasn't Crocker who killed Mike, it was Edna. Mike came to see Crocker and met Edna instead. It was she who didn't want to share their fortune, not with Mike - nor with his mother 20 years ago. Connors remembers that Edna's maiden name was DeSoto. The park ranger is not only Edna's accomplice but also her brother.
Thanks to Connors, the murders of Zoe Sharp and Mike McMillan have been solved, giving Connors closure and one last moment of glory.