In September 1938, a string of secret, advanced British aircraft prototypes vanishes along with their crews during test flights, leaving behind a riddle that stumps everyone involved. At the center of the effort is spymaster Major Hammond, Ralph Richardson, who finds himself an outsider at the Barrett & Ward Aircraft Company factory, where government contracts color every decision. He is joined by his sister Kay, Valerie Hobson, a fearless newspaper reporter who has slipped into the works undercover, determined to uncover the truth from the inside. As the mystery deepens, the tension inside the plant grows, with suspicion and secrecy casting long shadows over the people who work there.
Hammond’s investigation leads him to a pivotal ally in Tony McVane, Laurence Olivier, a star pilot whose skill and courage make him a natural partner in the hunt for answers. Together they begin to pry open the circle of potential informants and suspects, hoping to disentangle the web of clues that bind the disappearances to a hidden threat. But Hammond’s instincts point toward Jenkins, the factory’s seemingly loyal company secretary, George Curzon, as a possible mole—someone who might know the names of covert links and contacts. Before Jenkins can reveal anything, he is cut down by a gunman firing from a moving car, a brutal reminder of how dangerous the case has become.
The mystery takes a darker turn when Tony’s own aircraft is downed by a mysterious, overwhelming ray from the enigmatic salvage ship S.S. Viking. The ship’s crews, whose true allegiances remain ambiguous, operate with a cold efficiency that suggests a deeper plot at work. Tony and his downed crew are forced to surrender and are taken aboard the Viking, where Tony discovers a disturbing gathering of missing airmen who have suffered similar fates. The atmosphere aboard the ship is tense and claustrophobic, but hope survives as Tony orchestrates an audacious escape, moving through the vessel to seize weapons and gain control over their surroundings.
Back in London, Hammond pieces together the truth and responds with decisive action, directing a Royal Navy counter-move to rescue the stranded pilots. The climactic effort underlines the fragile balance between innovation and danger, as national security hangs in the balance and the moral lines of loyalty are tested. Amid the danger and deception, Kay and Tony’s bond grows stronger, offering a rare personal light in a world of shadows. Yet Hammond’s personal story takes a bittersweet turn when he finally reunites with Kay only to learn that she has married someone else, a revelation that adds a final note of melancholy to the mounting tension and the high-stakes drama surrounding the missing airmen and the looming threat behind their disappearance.
