Ken Franklin and the International Detective Agency operatives assist the Paris police when a baby is stolen from a local hospital and held for ransom. The search for the kidnappers sends the detectives scrambling from Marseille, Lucerne and the Montmartre District of Paris in search of the child.
The Burns International Detective Agency is hired to track down the criminals who printed scores of fake Rose Bowl tickets. The trail leads to England where the crooks pulled the same scam at Wembley Stadium. Franklin discovers the gang is now moving to bigger things - forging Belgian gold certificates.
When a woman engaged to be married to a pilot repeatedly flees from her home, her fiance engages the International Detective Agency to find her and learn what is causing her fear. They decide to look into her past and discover she was put up for adoption by her Austrian parents. The detective follow her parents from Vienna to Paris and ultimately to the United States to discover the roots of her unhappy past.
When an employee of a movie theater chain represented by the International Detective Agency is shot, the company steps in to assist the police with their investigation. The gang responsible goes on to steal tommy guns from National Guard armories, rob banks and kill cops in the process. The private detectives discover a link between the crooks and confederates in Rome and pursue the gang leader to Italy.