When Castle and Beckett go to get their marriage license, they find out that Beckett got married to Rogan O'Leary at the Drive-Thru Chapel of Love in Vegas while in college. Beckett needs to have him sign papers to end the marriage so she and Castle can get married in three days.
Rogan is a degenerate criminal who refuses to sign until Beckett helps him steal something, then he is abducted. He was trying to blackmail a local pastor for frequenting a strip club and uncovered a hidden mobster. Castle and Beckett manage to save him and he signs the papers.
When their venue and Kate's dress are destroyed, they move the wedding to the Hamptons and Kate wears her mother's wedding dress. But Castle never shows. An SUV runs Castle's car off the road. When Kate gets the call, she runs to the scene to find Castle's car in flames.