He tells Gus what he found, who wonders why, if they killed someone, are Howie and Eileen still there dancing with their classmates. Shawn and Gus head to the library to do more investigating, where they scour the yearbook to discover that Howie and Eileen had a third wheel in high school, always hanging around worshiping them, trying to be their friend. His name is not listed, but Gus finds a picture of him in auto shop class. Shawn goes to the shop classroom to find any clues to the guy's identity, where he comes across Henry sitting alone in a car, reliving his high school days. The door to that classroom was already unlocked, Henry says. Shawn finds an empty beer can in the car and a picture of his mystery man with his name on it, Peter Coulter.
Shawn and Gus go with Juliet to the police station to do a background check on Peter, where they discover that he was involved in an alcohol related car accident in high school. He hit a pedestrian who went into a coma and died a few months later. Howie and Eileen were in the car with them. Looking at pictures of the crime, Shawn sees a bruise on Howie's forehead from the steering wheel and the driver's seat shifted back as if a tall person were driving. It was Howie who was driving the car and Peter covered for him, not realizing the victim would eventually die. Juliet also tells them that Howie and Eileen recently took out a restraining order against Peter. Just then, Chief Vick shows up, warning them they shouldn't be using police resources when they haven't been assigned a case. Lassiter covers to for them, saying they were helping him bust Mindy, the worst date of his life, who has been filling prescriptions under a false name for years.
Shawn and Gus go back to where Shawn claims the body fell and they realize Howie and Eileen must have shoved the body down the window into the girls' locker room. They go in to find Peter's body there, hidden inside the mascot costume. But the killers arrive to finally get rid of the body for good, so Shawn and Gus have to act quickly before the evidence is destroyed. Chased by Howie and Eileen, they grab the body and run to the gymnasium to find Lassiter and Juliet. There, after Gus announces they have won reunion king and queen, Shawn tells everyone the truth about the accident in high school. Peter had covered up Howie's part in it all these years to protect his idol's scholarship, but when Howie decided to run for office, Peter couldn't keep quiet anymore and repeatedly tried to contact them. He finally tracked them down at the reunion, and, drunk, confronted them on the roof, where they pushed him off, silencing him for good. With the case over, Shawn is able to finally, after thirteen years, share a kiss with Abigail.