This is a fairly routine murder mystery. An armored car is held up, and its stolen bank notes turn up at a circus. Genn, a Scotland Yard investigator, is sent out to solve the case. The corpse of one of the robbers is discovered, and soon circus performer Margaret Lee is dead as well. The
chief suspects are Christopher Lee, a lion tamer who wears a hideous black mask to cover his scarred face; Drache, a ringmaster who is convinced his father was killed by Lee's twin brother; Kaufmann, a knife thrower driven crazy with jealousy over the dead Lee's other suitors; and Martin, a dwarf
known as "Mr. Big" who is blackmailing Lee. Other possible culprits include Arent, a ...