After eluding capture and disappearing eight years ago, the famed Yin Yang serial killer is back, and he's set his sights on Shawn.

Shawn and Gus are hired by a childhood friend to find a missing camp counselor who disappeared near their old sleep-away campgrounds. Upon their arrival, spooky activity abounds and they must uncover if the dark past of the abandoned camp has come back to life.

Shawn and Gus attend their high school reunion. Shawn sees a body fly past a window, but on further inspection the body has vanished. When Gus assumes the worst, and Lassiter refuses to help, Shawn seeks assistance from Juliet.

Gus is taken hostage at the Santa Barbara Savings and Loan Bank while making a deposit for Shawn. Shawn, still in the car and oblivious to the hostage situation, questions Lassiter and Juliet about the cops' sudden arrival. Learning that his best friend is in trouble, Shawn is desperate to help and realizes he needs to get inside the bank to question the gunman. However, the SWAT team soon shows up, and its negotiator will not easily satisfy Shawn's request.

Shawn and Gus must prove Lassiter's innocence when he's on the hook for a murder inside of the Santa Barbara Police Department.

Henry's brother, Jack, claims that he has a map that leads to buried treasure. Shawn and Gus assist Jack in his search for the treasure, but it turns out that Jack has got more going on than meets the eye.

Eugene Franks, arrested by Henry in 1978 for plotting to bomb the SBPD, is released after his conviction is quashed by the D.A. When Shawn is instructed to solve the case, his father insists on helping him; however, the case is not as clear cut as he once thought.

Shawn and Gus investigate a department store Santa who they suspect is up to no good. Meanwhile, Gus' sister flies in for Christmas.

Gus' supervisor, Frankjim Ogletree, demands that he quit moonlighting at Psych, lest he face termination. The vice-president of Gus' pharmaceutical company, however, decides to hire the duo as his wife believes that their home is haunted.

A surveillance tape from the latest robbery in a string of break-ins leads Shawn to believe that women are the culprits. He futher narrows the suspects down to a local roller derby team and suggests that in order to pinpoint the people responsible, Juliet needs to go undercover as a member of their team. Though it's technically her investigation, Shawn can't help getting involved in the case.

Shawn and Gus join up with a local firehouse to prove a series of arsons are more than they seem.

Shawn and Gus go undercover at a professional football training camp when the foot of the team's missing kicker is discovered.

When Shabby the sea lion is found dead after being released into the wild, Shawn sets out to prove it was murder and stumbles onto a bigger mystery.

Shawn and Gus must prove a pathological liar is telling the truth in order to stop an assassination plot.

Shawn and Gus get hired by the son of daredevil Dutch "The Clutch" Jenkins. They have to figure out what's going on, after "accidents" keep happening to The Clutch.

Shawn and Gus investigate the death of a safety inspector aboard an offshore oil rig. The investigation is complicated by the commander of the coast guard, Barbara Dunlap, Chief Vick's sister.