Sarah is rushed to the hospital after her nose starts bleeding and she collapses at their rehearsal dinner. Chuck goes on a search for Alexei Volkoff since he is the one that knows the Norseman's antitode. Chuck and Casey break into the prison and find his cell empty. They find out that it was Clyde Decker from the CIA who let Volkoff out because they want to put an end to all the Volkoff and Agent X intel. Decker tells Chuck to let it go, but Chuck is determined to finding Volkoff to save Sarah, even if it risks his job.
General Beckman gives Chuck clearance to go to Castle. Casey and Chuck's mom go with. They find Volkoff, but it turns out that he is dead. Decker extracts the persona out of Volkoff, leaving them with Hartley Winterbottom. Winterbottom is having a hard time remembering Volkoff, or the past thirty years at that. Although, he does have the information to create the antidote. They rush it to the hospital and give it to Sarah. It turns out that this antidote only added a few hours to her life - they need to go to Moscow to get the more advanced version of the antidote. They set off, but soon after Chuck is taken down by Decker.
Decker gets rid of Chuck's intersects and fires him. Casey comes and helps Chuck and Volkoff escape. They arrive at Volkoff Industries in Moscow to get the antidote from Vivian. Casey offers Chuck two clean identities for him and Sarah, and if she lives, the two have to disappear forever with their new identities. Hartley cannot speak to Vivian and he runs out. Chuck approaches Vivian and tells her the truth and please for her to give him the antidote. Vivian pulls a gun on him and to both of their surprises, Hartley comes back in and reveals that he convinced Stephen Bartowski to use the computer program to help him. Chuck offers Vivian two clean identities for herself and Hartley in exchange for the antidote.
Chuck arrives at the hospital faced with Decker and his men waiting for him. Then, Volkoff's men swoop in and take down Decker's army. We flash to Chuck and Sarah's wedding. Then, weeks later, Chuck returns from his honeymoon. Jeffster are bummed about the possibility of selling the Buy More. At an empty castle, Decker tells Chuck via computer screen that everything was part of the plan, and that Volkoff has given them $877 million as a wedding gift. They use this money to buy back the Buy More and buy Castle and they plan to become private spies. The team is back together, and Morgan puts on the sunglasses left by the General for Chuck, and the intersect is downloaded into Morgan's brain.