British scientist Peter Brady, while working on an invisibility formula, suffers a tragic accident which turns himself invisible. Unfortunately, there is no antidote, so, while working on a method to regain his visibility, he undertakes missions for his government stopping bad guys.

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.

When his colleague is killed during a chase in Kentish Town, London bobby Frank volunteers to become a dog-handler.