Mavis Ironmonger is nobody's idea of a good diplomatic wife. She drinks too much, she's awfully friendly with the staff at the Washington embassy, and her music-hall roots have a way of bursting out at the most inappropriate moments. Indeed, it's at an embassy reception that Mavis manages to insult a visiting ambassador and get herself hauled off to sober up.
With the party winding down, Mavis is due downstairs, to say the official goodbyes, but in fact she has already made her final farewell, courtesy of a gunshot. The ambassador refuses to allow the Americans to investigate, demanding instead that Henry Tibbet be called in from London. But if you know Henry, you know he won't be staying in DC; in an eyeblink he is headed to the ambassador's island nation, before haring back to Washington to prevent a second murder.