An international criminal arrives in London, and a detective is anxious to pin something on him for some unprovable murders of former lovers. The villain starts to suspect servants and henchmen of being a police spy known as 'Number Six'.

Burglars rob a townhouse and most of them are caught at the scene, but valuable jewels seem to have vanished. An estate agent realises they are still on site, and tries to purchase the building before anyone finds them.

A businessman's fraudulent dealings kills many people. His partner threatens to expose him if he has further dishonest dealings. When the fraudster receives death threats he fakes his own murder to get his hands on the partner's evidence.

A German immigrant seduces a young P.C. and talks him into an elaborate scheme.

A gang of thieves are implicated in a murder while executing a jewellery shop heist.

Carol Halston discovers her sister withdrew £7000 before she died. The money is now missing.