Among the mourners at the funeral of the great Soviet writer, Maxim Gorky, in 1936 was a mysterious baroness. Moura Budberg had been Gorky's lover and, before that, the lover of a British secret agent who'd been thrown into a Soviet jail. Her extraordinary life led some to call her the Russian Mata Hari. But was she really a spy?

(Photo: Baroness Moura Budberg. Credit: Hulton Archive/Getty Images)