Life always seems to be more complicated than it should be for Charlie Mortdecai: degenerate aristocrat, amoral art dealer, seasoned epicurean, unwilling assassin, and confirmed coward.

Something Nasty in the Woodshed finds Charlie exiled from London due to his growing unpopularity on account of some shady art deals. Taking refuge in a country estate on the Channel Island of Jersey, he embarks on a well-intended hedonistic interlude. But his vacation soon morphs into a macabre manhunt, as Charlie seeks to expose a local rapist whose modus operandi bears a striking resemblance to that of a warlock from ancient British mythology known as "The Beast of Jersey."