An ancient treasure, the Mercurial Mask, has been stolen from the British Museum. Richard Templar is charged with recovering the stolen mask. His mission is to reunite Margaritta Bonaparte with her elusive husband, the infamous thief, Jean Petize, who in return will reveal the whereabouts of the Mercurial Mask. From a Greek island prison to the deserts of Egypt, Richard faces rogues, mercenaries and madmen. On his quest, he is accompanied by Tannie Annie, an ex-soldier, Lans, the Australian barman, and Geoff, an ex-intelligence officer, as well as Jean and his wife Margaritta. With these unlikely allies at his side, he battles towards a final explosive confrontation with General Pretorious on the South Downs of Southern England.