Everything was going smoothly on the set of "The High and the Mighty" until the cast and crew returned from lunch. With one exception. Wiley Wyckham, the bit player sitting in seat 24A on the airliner mockup, is among the missing, and without Wyckham sitting in place, director William Wellman cannot continue filming. A studio wide search is instituted. No Wyckham. A lookalike is hired that night, filming resumes the next day and still no Wyckham. Except that by this time, it's been discovered that Wyckham, a British actor, isn't really Wyckham at all but an imposter who very well may be an agent for the Russian Government. The local police call in the FBI. The FBI calls in British counterintelligence. A manhunt for the missing actor ensues and Joe Bernardi, the picture's publicist, is right in the middle of the intrigue. Everyone's upset, especially John Wayne who is furious to learn that a possible commie spy has been working in a picture he's producing and starring in. And then they find him. It's the dead of night on the Warner Brothers backlot and Wyckham is discovered hanging by his feet from a streetlamp, his body bloodied and tortured and very much dead, and pinned to his shirt is a piece of paper with the inscription "Sic Semper Proditor." (Thus to all traitors). Who was this man who had been posing as an obscure British actor? How did he smuggle himself into the country and what has he been up to? Has he been blackmailing an important higher up in the film business and did the victim suddenly turn on him? Is the MI6 agent from London really who he says he is and what about the reporter from the London Daily Mail who seems to know all the right questions to ask as well all the right answers.