Down on his luck and guiding tourists through southern Africa, the wandering adventurer Anthony Cade accepts a simple-sounding job from an old friend: carry the explosive memoirs of a dead Balkan statesman to a London publisher, and quietly return a packet of compromising letters to a society widow. The errand turns out to be anything but simple. The fictional kingdom of Herzoslovakia has just struck oil, and the British government is maneuvering to restore its monarchy on terms favourable to an oil syndicate. When everyone with a stake in that throne converges on Chimneys, a grand English country house, a guest is shot dead on the night of his arrival, and Superintendent Battle of Scotland Yard arrives to untangle the affair. Around the killing swirl blackmail, mistaken identities, a notorious international jewel thief, and the rumoured whereabouts of a fabulous missing diamond. Cade finds himself drawn deeper into the intrigue alongside the genial Lord Caterham, his sharp-eyed daughter Bundle, and the charming Virginia Revel, all while a watchful French detective and a calculating Foreign Office official pursue their own ends. The story moves briskly between drawing-room comedy and political conspiracy, piling on secret passages, forged papers, and competing schemes. As suspects multiply and motives blur, the question is not only who fired the fatal shot but who, among the assembled players, is truly who they claim to be.