Chuck and Sarah's romantic mission is canceled with the arrival of Hugo Panzer and Heather Chandler. But Chuck grows more interested when the manipulative Heather claims to know a secret about his mom. Meanwhile, as Morgan prepares the Buy More for a huge video game release, he gets a surprise from Big Mike.

Afraid that his latest setback is driving a wedge between him and Sarah, Chuck resolves to prove himself by going on a dangerous mission with the overeager Agent Rye. Meanwhile, Morgan and Casey scramble as the "Buy Morons" attempt to uncover the true identity of Greta.

Chuck surprises Sarah with her old spy team, The C.A.T. Squad, leading to a mission in Rio. As The C.A.T. Squad works to settle a score with Augusto Gaez, old secrets and grudges come to light. Back at the Buy More, Morgan fends off the advances of Carina, a former flame and frisky member of The C.A.T Squad.

With the help of his old nemesis Alexei Volkoff, Chuck and the team hunt down a deadly weapon, The Norseman. In a pre-wedding surprise, Sarah springs a pre-nup on Chuck.

Before he can kiss the bride, Chuck must enlist his wedding party to take down Vivian Volkoff and stop her from destroying the big day. When he turns to Alexei Volkoff for help, the CIA sends its toughest agent, Clyde Decker, to stop them.

Without the Intersect in his head or the support of the CIA, the world of espionage is a much more dangerous place for Chuck Bartowski and his team of freelance spies. To start, Carmichael Industries takes on a slick, rich thief named Jean Claude, and a conniving investor, Roger Bale, who has stolen money from some of the world's most dangerous people. Meanwhile, Morgan helps Chuck with a special surprise for Sarah. Back in the Buy More, Jeff and Lester have taken things to another level with their latest scheme.

When a mission in Japan becomes a hostage situation, Sarah and Chuck must face the merciless Nicholas Quinn aboard a speeding Japanese bullet train. Meanwhile, the mission leaves Casey with an impossible decision.