Chuck is overcome with jealousy when his nemesis Bryce Larkin -- and Sarah's ex-lover and partner -- makes an unexpected return. Chuck and Sarah's growing feelings for each other are tested when their latest mission requires Sarah and Bryce to pose as an extremely affectionate couple. Meanwhile, Morgan faces his own challenge at Buy More when he must deal with a gang of bullies, from a neighboring sporting goods store in the strip mall called, the Mighty Jocks led by the fearful Mitt.

Life in espionage takes its toll on Chuck and everyone is taking notice. Chuck tries to explain his unusual behavior to Ellie and to the quirky Buy More efficiency expert Emmett Milbarge, but a new assignment only complicates things. After a global terrorist comes searching for Jeff, Chuck is forced to socialize with Jeff in order to find out what role the oddball plays in the mission. Sarah, Casey and Chuck are all shocked when they discover that the fate of the world and the prevention of World War III rest in Jeff's hands.