Xanthe Schneider is the American heroine of three e-thrillers about British naval intelligence from 1940-1 and the cracking of the Enigma code.
You may also be interested in the following ebooks and paperbacks about Enigma as non-fiction…
Alan Turing: Unlocking the enigma
Operation Primrose: U110, the Bismarck and the Enigma Code
Before Enigma: The Room 40 codebreakers of the First World War
Enigmas: Alan Turing and the codebreakers of the world wars (all three non-fiction titles bundled together for kindle)