Circus of Fear (German: Das Rätsel des silbernen Dreieck / Mystery of the Silver Triangle), also Scotland Yard auf heißer Spur, also Circus of Terror) is a 1966 Anglo-German international co-production thriller film starring Christopher Lee, Suzy Kendall, Leo Genn and Cecil Parker. The U.S. title was Psycho-Circus. It was based on the novel Again the Three Just Men by Edgar Wallace (1928).It was shot at Hammer Film's Bray Studios in Berkshire and on location around London.The film was partially shot at Billy Smart's Circus. The film was co-produced by the leading German distributor Constantin Film, which was at the same time releasing Rialto Film's long-running series of Wallace adaptations in Germany. Several of the cast Heinz Drache, Eddi Arent and Klaus Kinski were regular performers in that series and were added to this production to appeal to German audiences. Werner Jacobs directed the version release in West Germany.