King employs a first person narrator and opens with the protagonist (named "Norris") in the clutches of a wealthy, cruel criminal overlord ("Cressner") intent on exacting revenge on Norris, who has been having an affair with his wife. Instead of killing him outright, Cressner reveals his penchant for striking wagers, and offers a chilling ultimatum: if Norris is able to circumnavigate the titular 5-inch ledge surrounding the multistory building which houses Cressner's penthouse, he can have Cressner's wife, along with twenty thousand dollars, no strings attached. If he refuses to take the bet, he'll be framed for heroin possession and never see his lover again.
Seemingly without any other choice, Norris accepts the wager, and proceeds to carefully make his way around the building's cold, windswept exterior. Norris encounters multiple obstacles, including an obstinate pigeon. The narrator completes the harrowing ordeal, only to discover that Cressner had already murdered his unfaithful wife. Mad with rage, Norris overpowers Cressner and his bodyguard and takes the bodyguard's gun, and turns the tables on him, proposing to spare his life if only he is able to complete a trip around the ledge. However, as Cressner starts out, Norris reveals to the reader that he has been known to "welch" on bets, implying that he will kill Cressner even if he completes the task.