1936. A Soho night-club singer and daytime artist is recruited by the Secret Service. First they insert him as a cabaret singer on a German transatlantic liner with the task of spying on prominent passengers. As war clouds gather in Europe they move him to Paris with a new cover role as an artist and a mission to set up a spy network. When Paris is occupied they order him to become a portrait painter for the Nazis, so that he can fish for information during portrait sittings. This leads to him painting 'The Hitler Canvas'; unwittingly creating a portrait that possesses dark, supernatural elements. After the war he searches for the sinister painting, which he finally locates in 1983 in the ownership of a former SS officer. Now he plans to destroy it.