American, British, and Russian scientists collaborate on an atomic rocket. The rocket is launched from Australia, carrying astronaut John MacLaren. Before he leaves the earth's atmosphere, a breakdown occurs and he is forced to detach himself from the main rocket, which goes on to crash into the sun. The enormous force of the explosion sends a group of asteroids hurtling toward the earth. Strange phenomena, including animal migrations, tidal waves, typhoons, heatwaves, and other catastrophes, inspire panic on earth. The scientists reveal their true mettle; some panic and others go mad. Some, MacLaren among them, resolve their personal problems and study the situation. In his desperate effort to save the earth, MacLaren organizes an international scientific team, and all governments are persuaded to cooperate. At a given time, rockets carrying the world's stockpile of atomic weapons are launched from all over the earth, and the asteroids are exploded.