In 1996, star athlete Calvin Joyner is being honored at his high school. Halfway through Calvin's speech, Trevor Olson and a group of bullies throw a naked Robbie Weirdicht, who was showering, into the hall where the assembly is taking place, embarrassing him. Only Calvin and his girlfriend, Maggie Johnson, are sympathetic towards Wierdicht.

Twenty years later, Calvin is married to Maggie and works as a forensic accountant but is dissatisfied with his career. Maggie suggests they see a therapist to salvage their deteriorating marriage. At work, Calvin receives a friend request on Facebook from a man named Bob Stone, who reveals that he is Wierdicht and requests that they meet. Calvin is shocked to see that Wierdicht has transformed into a muscular, confident CIA agent. Stone asks Calvin to review a few accounting records. Calvin deciphers the records as multimillion-dollar transactions from an auction, with the final payment set to be made the following day. Stone avoids Calvin's questions and spends the night on his couch.

The next morning, a group of CIA agents led by Pamela Harris arrive at Calvin's house in search of Stone, who escapes. Harris tells Joyner that Stone is a dangerous rogue agent who intends to sell satellite codes to the highest bidder. Soon after, Stone abducts Calvin and explains that he is trying to stop a criminal known as the Black Badger from selling the codes but needs Calvin's skills to find the coordinates of the deal's location. After an attack by a bounty hunter, Calvin flees and calls Maggie, telling her to meet him at the marriage counselor's office. Harris intercepts him and tells him that Stone murdered his partner Phil Stanton and is the Black Badger himself. She warns him to refrain from telling Maggie and gives him a device to alert them to Stone's location. Calvin then arrives for marriage counseling, where he finds Stone posing as the counselor.

Bob convinces Calvin to help him, and Calvin sets up a meeting with Trevor, who is able to track the offshore account for the auction, so they can get the deal's location. Trevor helps them and said that he's found God but he lies and laughs in their faces and bullies Bob once again. Harris calls Calvin and threatens to arrest Maggie if he fails to help them detain Stone. Calvin is forced to betray Stone, and the CIA arrests him. As Harris tortures Stone to get him to confess, Calvin decides to help Stone escape. Calvin deduces that the deal is happening in Boston and helps Stone steal a plane. At an underground parking garage, where the deal is assumed to be taking place, Stone enters alone, while Calvin sees Harris entering a short while later. He mistakenly assumes that she is the Black Badger and runs after her, but finds Stone meeting with the buyer and claiming to be the Black Badger. Bob shoots Calvin, grazing his neck, to keep him safe.

Phil arrives, revealing that he is alive, and claims he is the real Black Badger. The buyer attempts to retrieve codes from both Stone and Stanton, but the CIA arrives and a shootout begins, while Calvin grabs both codes and runs outside. He encounters Stone and Stanton, who engage in combat. Unable to decide who is the criminal, Calvin randomly shoots Stone, but Phil confesses that he is the Black Badger and that Bob is innocent. Calvin causes a distraction that allows Bob to rip Phil's throat out, killing him. The two deliver the codes to Harris, who then drops them off at their high school reunion, where Calvin reconciles with Maggie. Bob is announced as the Homecoming King, with Calvin revealing to Maggie that he hacked the voting system to ensure Bob's win. Trevor attempts to bully Bob a third time, but Bob knocks him out. As Bob delivers his speech, he relives his most embarrassing high-school moment and takes off all his clothes confidently. He walks off stage to unite with his high school crush Darla McGuckian.

Before the ending credits, Maggie is pregnant and Calvin has joined the CIA. As a gift for his first day on the job, Stone gives Calvin back his varsity jacket from high school, which Calvin had given to him after the senior assembly prank.

Award Category Recipient(s) Result
Critics' Choice Awards Best Comedy Central Intelligence Nominated
Best Actor in a Comedy Dwayne Johnson Nominated
Golden Trailer Awards Best Comedy "Trailer 1" Nominated
Best Comedy Poster "Big Johnson Teaser" Nominated
People's Choice Awards Favorite Comedic Movie Central Intelligence Nominated
Favorite Comedic Movie Actor Kevin Hart Won
Dwayne Johnson Nominated
Teen Choice Awards Choice Summer Movie Central Intelligence Nominated
Choice Summer Movie Star: Male Kevin Hart Won
Dwayne Johnson Nominated