U.S. Embassy employee Lee Cochrane and his wife, Sue, receive a shock when they discover that their 18-month-old son, Simon, has disappeared in London. He was last seen with their nanny, and the couple seemingly have no leads that might help police Detective Craig in his investigation. The media sensationalizes the incident, causing an unnecessary distraction as the couple prepares to confront the culprit face-to-face.

Stanley Baker's O'Donovan is sent to steal the plans of a rival company's racing car designs, to ensure his employers win the competition. However, when opening a safe containing the plans, he triggers an alarm leading to a gun battle where he kills a number of people. James Robertson Justice, alarmed by the scandal surrounding the killings, orders his agent be killed surreptitiously to hide his involvement with the plot. The film uses original footage from the Mille Miglia , an Italian open-road endurance race, featuring classic period racing cars.