In the deep and vast outer space, the blue Earth contrasts sharply with the bottomless, pitch-black universe. A space station belonging to the United States is in use, where several astronauts are conducting a spacewalk and performing routine checks on their respective satellites. Dr. Ryan Stone (played by Sandra Bullock), who is venturing into space for the first time, is methodically checking every component with the assistance of the experienced astronaut Matt Kowalsky (played by George Clooney). This is Kowalsky's final flight before retirement, and he livens up the team's atmosphere with his humor. At this moment, a shocking message comes from headquarters in Houston: a Russian satellite that was set to be decommissioned has just been destroyed by a missile, scattering debris at speeds exceeding that of bullets in Earth's orbit, which unexpectedly hits other satellites, triggering a chain reaction that creates even more debris. Ryan and her companions are severely hit by the debris, with some unfortunate casualties, and she and Kowalsky lose control and fall deep into the universe. The two survivors are forced to trust each other and do everything they can to head back home...