When Germany invades Holland in 1940, a British intelligence officer and two Dutch diamond merchants go to Amsterdam to persuade the Dutch diamond merchants to evacuate their diamond supplies to England.

Suave private investigator Norman Conquest intercepts a secret message and meets a beautiful but foreign blonde lady in room 605 of the Park Plaza hotel. But when Conquest wakes up in the room the next morning he is lying next to a dead body. With the mysterious blonde nowhere to be seen, Conquest soon becomes the police s number one suspect with Inspector Williams following his every move. In order to clear his name, Conquest enlists the help of Pixie Everard (Joy Shelton), but the going gets rough when he discovers that the murder is connected to a stash of stolen diamonds. As gun-happy gangs of communists and Nazi sympathizers turn up the heat, Conquest has to solve the murder whilst staying one step ahead of both the gangs and the police.

An adventurer is hired by a German millionaire to help a Polish scientist escape to the West.

A rocket engineer, responsible for sending a satellite into space, is accused of committing the most extraordinary crime.

Private eye Edward Mercer travels to Venice to locate a man due a reward for his aid in the war. Shortly after arriving, he becomes the prime suspect in the murder of his local contact. In his quest to clear his name, Mercer uncovers a conspiracy. Even the local magistrate seems to be working against him, and Mercer begins to suspect the man he came to find is behind it all.