Ellie helps Sarah plan what seems to be a small bachelorette party while Awesome plans an elaborate bachelor party for Chuck in Vegas. Chuck and the guys end up at Las Vecas, a calm camping ground - absolutely not what was expected. Sarah's low-key spa day became a wild party, which included male entertainers.
Vivian Volkoff and team are on a mission to find the contents of Chuck's dad's laptop to find information on Agent X. They are lead to Las Vecas, since Awesome and Ellie accidentally swapped bags. Riley gets a hold of the laptop while Casey tries to save everyone. Casey takes one mercenary down one at a time. They regain control and retrieve the laptop, which now has a knife hole in it. They leave the campground in a limo.
Chuck takes Ellie aside and tells her the truth about his spy life. She visits Castle and learns that the Intersect is actually in Chuck. Ellie has some valuable information for Chuck and team – Chuck cannot be Agent X since the project was dated before Chuck was even born. Chuck fixes the computer and finds the name Hartley. He experiences a flash of a picture of a house in England. The team head off to England to investigate. An elderly woman invites them into the home and she ends up holding them at gunpoint. She says that the CIA has corrupted her son. She realizes that Chuck is Steve Bartowski's son and sets her gun down. Soon after, Vivian Volkoff's team charges in and attacks. Chuck and Sarah sneak down to the basement and discover Agent X's "spy will."
Meanwhile, Big Mike, Jeff, and Lester are still bummed about how the bachelor party turned out. They decide to drive to Reno. They fall asleep during their drive and end up in Canada, where they spot a casino! The team returns to Castle and discover that Hartley is their Agent X. They look at the photo and it is of Alexei Volkoff. Casey makes the executive decision to hide this fact, that the CIA has unintentionally created a powerful enemy. Chuck and Sarah come to the conclusion that their father wanted them to go on this mission to fix Agent X.