When a nobleman is threatened by a family curse on his newly inherited estate, detective Sherlock Holmes is hired to investigate.

A hard-nosed Chicago cop is sent to London to bring back an American mobster being held for extradition. Brannigan in his Irish-American way brings American law to the people of Scotland Yard but has to contend with a stuffy old London first.

Marine atomic tests cause changes in the ocean's ecosystem resulting in dangerous blobs of radiation and the resurrection of a dormant dinosaur which threatens London.