Based on the novel QUEEN IN DANGER, written in 1952 by the English novelist and playwright Elleston Trevor: born Trevor Dudley-Smith, he mostly used the pen-name Adam Hall but several pseudonyms, as well (Simon Rattray, Howard North, Roger Fitzalan, Mansell Black, Trevor Burgess, Warwick Scott, Caesar Smith and Lesley Stone). The novel was adapted to a screenplay by the legendary English film director and editor Terence Fisher (who also dIrected the movie for Hammer Films) and the prolific Hungarian author, essayist, novelist, journalist -and screenwriter- Paul Tabori. Produced by the English screenwriter, director and producer Michael Henry Carreras and the Hungarian writer, director and producer Alexander Paal. Filmed near St. Paul's Cathedral in London. THE GREAT STAR of the movie is Paul Henreid (the double or doppelganger) of the philosopher Albert Camus) in the role of Hugo Bishop: this is the 2nd book from Elleston Trevor's ''Hugo Bishop'' series, the 1st being ''KNIGHT SINISTER'' (1951), the 3rd being ''BISHOP IN CHECK" (1953), the 4th being ''PAWN IN JEOPARDY" (1954) and the 5th being ''ROOK'S GAMBIT'' (1955).