Chuck wants to have several of Sarah's close friends attend their engagement party. He searches through the CIA database to try to piece together pieces of Sarah's past. He invites three girls, collectively known as the Cat Squad. The Cat Squad picks up Sarah in a helicopter and head off to her bachelorette party. Carina, part of the Cat Squad, life is threatened which brings Casey, Morgan, and Chuck to the party. Chuck discovers the thread through a flash and Chuck leads them to Gaez, an old enemy of the Cat Squad.
Morgan is forced to stay behind and take care of an old flame, while trying to stay true to Alex. The rest of the team is in Rio. Gaez captures the Cat Squad and they realize that someone has betrayed them. Gaez offers a compromise by asking them to work for him. Sarah gets a hold of Gaez but it is quickly broken up when Chuck crashes through the window. The Cat squad brings Gaez back for questioning. Before they get any information out of him, Amy reveals that she is the traitor and tries to break him free. Chuck users several flashes and takes down Gaez and Amy.
Morgan has been acting very weird and ultimately Alex breaks up with him. He fights his way back with Alex and tells her he loves her. Sarah, who has been keeping her distance from Chuck, apologizes to him and thanks him for all the work he's doing to help her family. She confides in Ellie, agreeing to talk about her family issues and asks her to be her maid of honor.