During wartime, Josephine Daunt, a Special Operations Executive operative in France, and Dervish, her controller in London, were engaged in exciting and dangerous work. But in peacetime they found themselves at a loose end. Though very different people - Daunt, Cambridge educated, meticulous and inquisitive, and Dervish, practical, energetic and instinctive - they work well together and form a private detective agency, enlisting the help of Bill Mackie, a former private detective, whose son had been killed in the war while working for SOE.

In the new fourth series Josephine's preparations for her marriage to Bill have to take a back seat when an up-and-coming young British fashion designer reports the theft of her latest designs. It seems a pretty straightforward case, but before too long Daunt and Dervish find themselves mixed up in a world of Teddy boys, political chicanery and sudden death.