Attorney General Maxwell's son Dylan is getting married. Only problem, the engagement ring, a family heirloom worth $5 million, has been stolen from the safe at the hotel where the wedding is to take place. Shawn, at the police station on another case, sneaks into the interview room where Dylan and his fiancé Bethany are waiting, along with Dylan's sister, and Bethany's maid of honor, Lacey. In the minute he has before Lassiter comes in and catches him, he's able to get all the information on the case -- along with an invitation to the wedding that weekend.
Spoilers ahead. Coverage follows the scope labeled below.
Complete story — includes the ending
A five-million dollar engagement ring disappears from a hotel vault. Shawn and Gus overhear the police discussing the case, and decide to take the case on their own. They visit the hotel where the ring was held, and discover several things from the police. Shawn gathers keys to all of the wedding ceremony's attendees, and talks with them. He becomes involved in the wedding, and helps with much of the preparations. While attempting to gather more clues, Shawn discoverers the police's main suspect dead. He "psychically" reveals this to the police. During the wedding ceremony, Shawn realizes who the perpetrator is, and interrupts the ceremony to reveal it.