Opening with Genesis quotes that set a grim frame, the film follows David Randall, a pilot who carries top-secret photographs from South African astronomer Dr. Emery Bronson Hayden Rorke to the United States. There, Dr. Cole Hendron is confronted by the alarming news: Bronson has detected a rogue star named Bellus and an Earth-sized neighbor planet named Zyra hurtling toward collision with Earth. Hendron, aided by his daughter, Joyce Hendron Barbara Rush, concludes that time is dangerously short—roughly eight months until Zyra’s close pass and then Bellus’s following impact would end civilization as we know it. The stakes are existential, and Hendron pleads for a plan to save humanity by building arks large enough to ferry a select group to Zyra in a faint hope of survival.
As the science and urgency deepen, two wealthy humanitarian backers step forward to fund the project: the wheelchair-using magnate Sidney Stanton John Hoyt, who agrees to support the ark but insists on a say in who gets to board, a demand Hendron resists by limiting decisions to the pool of qualified volunteers rather than letting money decide. The world reacts in parallel, with other nations starting their own hopeful vessels. Amid the mounting pressure, Hendron’s team begins assembling a crew and passengers, while the romance between Joyce Hendron and Pilot David Randall Richard Derr complicates personal loyalties; Randall’s devotion to Joyce is tested by the competing relationship he shares with her father’s mission and with Joyce’s fiancé, Dr. Tony Drake.
As Zyra nears, chaos spreads: martial law is declared, coastal cities are evacuated inland, and the world shakes with earthquakes, volcanic eruptions, and tsunamis. Dr. Bronson is killed in a crane accident during the turmoil, leaving Hendron and his team to press on. Randall and Drake, a medical doctor by trade, alternate roles in the relief effort—Randall delivering supplies on a helicopter while Drake helps at-risk communities from the air. In a defining moment, Randall rescues a stranded child from a flooded rooftop, an act that cements his indispensable status in Hendron’s eyes and in Joyce’s heart, even as Drake’s practical deception about a supposed “heart condition” of the pilot Dr. George Frye Stephen Chase nudges Randall toward accepting a crucial role as co-pilot.
With the crisis deepening, Hendron stages a ceremonial yet practical lottery to determine who will ride the ark. He reserves seats for himself, Stanton, Joyce, Drake, the pilot Dr. George Frye Stephen Chase, and Randall, plus the rescued boy, bringing the passenger total to 45. Randall, feeling unqualified, initially rejects his lottery win and pretends to draw a number, but Hendron sees through the ruse. Drake later reveals that Frey’s supposed heart condition could kill him at liftoff, persuading Randall that he is needed as co-pilot to balance the crew and ensure a safer launch.
Tension peaks as Stanton’s fear for the doomed losers drives him to stockpile weapons, and tragedy strikes when Ferris Harold Ferris, Stanton’s longsuffering assistant Frank Cady, is shot dead by the magnate in a bid to force his way aboard. Hendron then makes a bold, desperate call: he launches the ark prematurely with several outsiders still outside to conserve fuel and maximize the chance of reaching Zyra. The crew blackout under the acceleration, and only after Randall awakens do they learn that Drake had misled them—Frey had died in the confusion, but the ship’s real pilot is now at the controls.
Once the ark breaches Zyra’s atmosphere, the fuel runs dry and Randall takes the helm, guiding a courageous landing on snow. Zyra, once deemed a death sentence, reveals itself as habitable, offering a glimmer of new life for the chosen few. Joyce and Randall emerge among the first survivors, walking hand in hand down the ramp as a new day dawns, with the distant silhouette of an artificial structure looming in the background, suggesting that humanity’s next chapter—and perhaps a renewed civilization—has begun on this unexpected world.
