Nobby (Sacha Baron Cohen), a sweet but dimwitted English football hooligan, reunites with his long-lost brother Sebastian (Mark Strong), a deadly MI6 agent, to prevent a massive global terror attack and prove that behind every great spy is an embarrassing sibling.

Nobby has everything a man from Grimsby could want, including 11 children and the most gorgeous girlfriend in the northeast of England (Rebel Wilson). There's only one thing missing: his little brother, Sebastian, who Nobby has spent 28 years searching for after they were separated as kids.

Nobby sets off to reunite with Sebastian, unaware that not only is his brother MI6's deadliest assassin, but he's just uncovered plans for an imminent global terrorist attack. On the run and wrongfully accused, Sebastian realizes that if he is going to save the world, he will need the help of its biggest idiot.