Gus must re-team with his estranged college singing buddies when a member of the old quartet is murdered.
A man on a bike pedals for his life, being chased by armed assailants. He reaches his apartment building, drops his bike and runs inside. He pulls a digital camcorder from his backpack and is able to email out its contents before the men break in and asphyxiate him. This man, it turns out, is Leonard “Diddle” Callahan, and a college friend of Gus’. Shawn and Gus attend Diddle’s funeral, where the minister says Diddle died from a hit and run accident on his bike. There, Shawn discovers, that not only was Gus in a singing group, but he has been estranged from Diddle, Tony and Joon for years and refuses to say why. Shawn also notices a mourner with a scar on his face who seems out of place there. Tony and Joon are able to speak to Shawn alone. They tell him Diddle was way too careful on his bike to die in an accident. They believe he was murdered, and they hire Shawn to find out what happened.
In the Psych office, Tony and Joon tell Shawn about the email they got from Diddle the night he died. Titled, “It’s so hard to say goodbye,” the email came with a large, heavily encrypted attachment. Diddle worked for Cybervault, a company that encrypts data for other companies and the government. The guys think Diddle must have run across secret information someone else wanted. They all head to Diddle’s apartment where Shawn notices how meticulous Diddle was. He sees new hinges on the door and Diddle’s bike safety gear hung neatly on the wall – gear he would never leave behind on a bike ride. Shawn also notices some of Diddle’s computer gear is missing and decides it’s time to bring in the cops. But Lassiter and Juliet uncharacteristically shut them down, so they are forced to sneak into the coroner’s office where they discover Diddle’s injuries are consistent with asphyxiation. The accident was used to cover the murder, which means, since Gus, Tony and Joon received the emailed file, their lives are now in danger, too. As Shawn and Gus report this back to Tony and Joon, Tony’s car blows up in front of them.