Gus is in charge of his and Shawn's high school reunion and he wants the night to go perfectly. He warns Shawn not to mess things up, then instructs him to go find more folding chairs. While Shawn heads to the cafeteria with Abigail, his high school crush, he sees, out the window behind her, someone fall to their death from the roof. But by the time they grab Gus and head outside, there is no sign of a body. Gus and Abigail don't believe anything happened, but Shawn claims the victim was wearing a letterman's jacket and, after they walk away, he spots part of a lapel pin in the grass.

Shawn, Gus and Henry return from a night at the movies to find that Henry's younger brother Jack is back in town and has broken into the house. Shawn finds him crouched by the coffee table in the living room. The guys are elated to see him but Henry is less than thrilled. Where they have always been enamored by Jack's wanderlust and fantastic stories of his worldwide adventures, Henry has always known his younger brother to be unreliable and irresponsible. Jack always wants something, and when Henry questions his motives for being back, he confesses that he wants their help to find the French pirate Bouchard's hidden treasure. Henry claims the legend of Bouchard's cache of stolen Spanish gold is just a story and the treasure doesn't exist. But Jack proves him wrong as he pulls out an ancient treasure map he discovered while traveling in Argentina. See, Bouchard, after a battle with the Spanish fleet and the Chumash Indians, made off with the gold then disappeared at sea, only to turn up in Argentina years later. Now Jack, armed with a map and a psychic detective, is positive he can find the treasure, and offers Shawn and Gus a fifty-fifty split. They jump on board.