"The Man Who Knew Too Little" is a comedic caper that follows the misadventures of Wallace Ritchie, played by Bill Murray. Wallace, an unsuspecting American, travels to London to visit his brother for a birthday celebration. Unbeknownst to him, his brother has arranged for a unique experience: a live-action theater performance where participants become part of the story.

However, when Wallace mistakenly believes that the entire scenario is real, he unwittingly gets caught up in a web of espionage and intrigue. As he navigates through a series of hilarious misunderstandings, Wallace's obliviousness leads him to thwart a criminal plot, all while thinking he’s simply playing a role in a theatrical production. The film cleverly blends elements of mistaken identity and slapstick humor, showcasing Murray's signature comedic style as he turns a simple visit into an extraordinary adventure.