An elite department within Interpol, Department S inherits those cases which the other member groups have failed to solve.

An elite department within Interpol, Department S inherits those cases which the other member groups have failed to solve. The brains of the group is Jason King, a hedonistic maverick who writes mystery novels and solves real-life crimes by projecting himself into the shoes of his fictional hero, Mark Caine. American Stewart Sullivan is the fighter and pragmatist of the group, as down to Earth and cynical as Jason is flighty and flamboyant. Annabelle Hurst is their scientist and analyst, whom Jason often accuses of loving nothing in the world except her computer. Although there is strong loyalty amongst the trio, there is also a lot of competition, especially between Annabelle and Jason, who seldom agree on any theory and are continually trying to show each other up by solving cases using their preferred methods. The head of Department S is Sir Curtis Seretse.