Chuck Bartowski is a socially awkward twenty-something who works as a computer expert at the Nerd Herd at his local Buy More (a parody of Best Buy's Geek Squad), a local electronics retailer (a CompUSA store was used), with his best friend, Morgan Grimes. Chuck's sister Ellie is a doctor who is constantly looking out for his best interests and wants to help him find a girlfriend. On the night of his birthday party, Chuck receives an e-mail from his former Stanford University roommate, Bryce Larkin, who is now a "rogue" CIA agent. When he opens it, an entire server of sensitive data — once only available to the United States government — called the Intersect, is subliminally embedded into his brain by way of a long series of images. Both the National Security Agency and the Central Intelligence Agency want the intelligence returned to them and dispatch agents of their own — Major John Casey and Sarah Walker — to retrieve that data.
Since the disk with the government information was stolen by Bryce and destroyed in his attempted escape, and since Chuck experiences flashes of information from the database activated by certain subliminal triggers, he must use the knowledge he now possesses to help the government thwart assassins and international terrorists — upending his previously uneventful life. Chuck's decision to keep his new-found occupation a secret from his family and friends and to live his life as normally as possible forces Casey and Walker to establish an uneasy alliance and secret identities (Walker poses as Chuck's girlfriend and takes a cover job at the local restaurant next to the Buy More, Wienerlicious, while Casey gets a job at the Buy More), with the shared goal of protecting Chuck at all costs.