Ep 11. In Plain Fright

In the Psych season 5 episode 11 titled "In Plain Fright," Shawn and Gus are invited to a convention for serial killers by an old friend, who is now a famous horror author. The convention takes place in a historic mansion, which is rumored to be haunted by the ghost of a murdered maid. As the convention attendees start to get murdered one by one, Shawn and Gus get embroiled in the mystery.

Shawn, still grieving over his father's death, is hesitant to attend the convention but decides to go with Gus to support his friend. At the convention, they meet a group of eccentric serial killers, including their host and author, Billy Lipps, who wrote a book inspired by the mansion's ghost story. Other notable attendees include a mother-son duo claiming to be "accidental" murderers, a man who dresses up as a clown to kill his victims, and a man who disguises himself as women.

As the party progresses, strange things start happening inside the mansion, including a locked room that no one can enter, a painting that appears to be watching them, and most disturbingly, the strange, unexplained deaths of the convention's attendees. Shawn, who initially thought the murders were part of a publicity stunt, soon realizes that they are all in grave danger and that the killer is amongst them.

Throughout the episode, Shawn struggles with his emotions, grappling with grief and guilt over his father's death. He's also forced to confront his fears and anxieties about death and mortality. At the same time, he uses his keen observational skills to solve the mystery of the murders, trying to piece together clues and motives that'll help him identify the killer before it's too late.

As the night wears on, the killers become increasingly paranoid and suspicious of each other, with tensions escalating to dangerous levels. The audience is kept on the edge of their seats as the twists and turns of the plot unfold. The episode features plenty of classic Psych humor and hijinks, including Shawn's signature pop culture references and Gus's hilarious reactions to the spooky goings-on.

Ultimately, the episode comes to a thrilling conclusion, with the killer revealed and justice served. Along the way, fans of the show get to enjoy some of their favorite Psych moments, from Shawn and Gus's playful banter to Shawn's impressive feats of deduction. In Plain Fright is a standout episode of the series, providing equal parts laughs and thrills while also exploring some of the show's deeper themes.