Sensitive documents have been turned over to enemy hands. Secrets involving the manufacture of an atom bomb have been betrayed. Now its in the hands of Scotland Yard to investigate, and resolve the matter, if they can. Contact men, passwords, covert transmissions, and cloak and dagger stuff abounds.
Working with Military Intelligence, urgency in finding the unknown culprit escalates, but he has a 3 month head start. Who had access to the documents? Do their alibis hold up? One by one, stories are checked out, and removed from the suspect list. Scientists, knowledgable men, responsible men, but who had a motive to sell out to an enemy?
Inspectors begin to wonder if they have been the victim of a hoax. Is there any missing uranium at all? A break comes when a photo is identified, and a highly placed crook is taken down.