Shawn's mom, Madeleine, is in town to do psych evaluations for the SBPD. During her return, Shawn is confused and disturbed by his father's friendly behavior toward her. As if things aren't bad enough, Gus is forced to stop working at the Psych agency when his boss notices that it is interfering with his work at the pharmaceutical company. He demands that Gus quit, lest he be terminated from his real job. However, the company boss has one more case for Shawn and Gusa "figure out who's haunting his house and get rid of whatever it is.

It took thirteen years, but Gus has finally finished planning he and Shawn’s high school reunion. While Gus tries to keep everything in order, Shawn catches up with an old friend, Abigail. Their chat is interrupted when Shawn supposedly sees a person fall to his or her death outside a nearby window. Though there’s no body on the ground below, Shawn is insistent about what he saw. He must quickly solve the crime that no one else believes happened before the murderer has a chance to escape.

Shawn and Gus score tickets to a daredevil show featuring Dutch The Clutch Jenkins. When he attempts a motorcycle jump through a ring of fire, Shawn notices his fuel line has been cut. Though Dutch emerges unhurt, Shawn concludes that someone must be trying to kill him. It turns out this isn’t the first accident that has happened recently. Unbeknown to Dutch, his son hires Shawn and Gus to figure out what’s going on. Unbeknown to Shawn and Gus, they must pretend to be stunt testers in order to keep Dutch in the dark about their true intent.

Shawn, Gus, and Henry return home to find an intruder in Henry’s house. The man turns out to be Henry’s brother, Jack. Jack, known to Shawn as the fun uncle, is a treasure hunter. He has returned to Santa Barbara in order to search for ancient Spanish treasure and needs the help of Shawn and Gus’ detective skills in locating it. However, recovering the treasure won’t be easy, as the group has to avoid interference from Jack’s previous partners and government officials, all of whom are also seeking the gold.

Thirty years ago, Henry solved his biggest case when he stopped an anti-government radical from blowing up police headquarters. However, due to a problem with the search warrant, the criminal now has been let out of prison, and the case must be reopened. Chief Vick puts Shawn in charge and insists that Henry not be allowed to participate, but that doesn't stop him from forcing his way in. Meanwhile, Lassiter and Juliet trick McNab into taking an undesirable case, leaving them free to take on a much more interesting one.

Chief Vick enlists Shawn and Gus to help investigate a recent death on an offshore oil rig. Although the Coast Guard has deemed it an accident, Vick suspects foul play based on an anonymous tip regarding the rig’s lack of safety. However, the location of the oil rig puts it out of Vick’s jurisdiction and into the hands of Coast Guard Commander Barbara Dunlap. Barbara is Chief Vick’s older sister, and while Lassiter finds himself attracted to her, Shawn and Gus find themselves in the middle of a sibling rivalry between the two sisters.

The surveillance tape from the latest robbery in a string of break-ins leads Shawn to believe that women are the culprits. He further 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. And with Gus busy studying for an important pharmaceutical rep exam, Shawn uses the opportunity to try getting closer to Juliet.

Gus makes a deposit inside the bank, leaving Shawn to wait in the car. While Gus stands in line, a man pulls out a gun and takes everyone there hostage. 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.

At the request of a little girl, Shawn and Gus get an imprisoned Santa released from jail. They congratulate themselves for saving Christmas but are disheartened to find out that the little girl conned them; Santa is actually her father, a known con artist. Shawn and Gus also overhear the two discuss a possible Christmas Eve heist. They enlist Gus’ sister, Joy, to help investigate the secret plans, while she and Shawn keep secret the fling they had ten years ago. Things get especially awkward when Shawn temporarily moves in with the Gusters.

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.

Lassiter has been charged with murder by the Santa Barbara Police Department, and Shawn and Gus are on the case to prove his innocence.

A series of arson’s has Shawn and Gus joining up with a local firehouse to prove they are more than they seem.

A foot of a missing football kicker is found during a football match. This looks and sounds suspicious. Shawn and Gus decide to go as Undercover football players in that professional football training facility to see what the reality is and investigate this case properly and find the truths hidden in it.

Ryan is a Pathological liar who has a history of tricking the police with her lies. She is the prime suspect for the killing in an assassination plot. Shawn and Gus are being called for help and now they have to convince the police that a liar is actually telling the truth about not being involved at all.

Jason Cunningham, Shawn and Gus' childhood friend has hired them to solve a case about a missing camp counselor who got missing in the old sleep away campgrounds. Soon Gus and Shawn realize that there is a psychotic killer who is stalking them and they being called was a trick to make them subjects of the killer.

Shawn get ready to ask out his high school crush for a romantic date. He very soon figures out that he is being targeted by a serial killer. Yin Yang, the serial killer who was away from a long time is now back.At the same time, Madeleline, gets kidnapped and now Shawn is on the case to solve it as soon as possible.