Perhaps Valentine Williams finest mystery thriller. Set in WW2, folk singer and guitarist Andrea Hallam gets caught up in a Nazi spy ring while travelling alone in Morocco.
Kidnapped by Nazis who believe she holds a dossier on Hitler, the tale travels from entertaining wartime banter to sinister suspense and back again. There are 7 books in the Clubfoot series of secret agent action novels, featuring Dr Grundt, an agent of the German government as the baddie.