For his first expedition aboard a space shuttle, Dr. Ryan Stone, a brilliant expert in medical engineering, accompanies seasoned astronaut Matt Kowalsky. But while it is apparently a banal walk in space, a disaster occurs. When the shuttle is pulverized, Stone and Kowalsky find themselves completely alone, left to their own devices in the universe. The deafening silence around them tells them that they have lost all contact with Earth - and any chance of being saved. Little by little, they give in to panic, especially since with each breath they consume a little more of the few reserves of oxygen they have left. But it is perhaps by sinking even further into the terrifying immensity of space that they will find the way to return to Earth...