There have been many remarkable women who served British Intelligence during the Second World War. One whose dubious claim to have worked for them is a fascinating tale involving three marriages – the first, to a spurious White Russian prince; the second to a playboy-turned-criminal involved in a major jewellery robbery in the heart of London's Mayfair in the late 1930s. After the war she became romantically involved with a well-known British Fascist, but finally married another notorious criminal whom she had met earlier during the war. The descriptions variously ascribed to her ranged from 'remarkable' and 'quite ravishing' to '…a woman whose loose living would make her an object of shame on any farm-yard'. Until now, very little has been recorded about Stella Lonsdale's life. She doesn't even merit a mention in the two official histories of MI5, even though she managed to tie them up in knots for years. This book will explore the role this strange woman may or may not have played in working for British Intelligence, the French Deuxième Bureau, or the Abwehr – German military intelligence – during the Second World War, using her MI5 files as a primary source.