When an ammonia leak threatens the astronauts on the International Space Station, NASA directs Lucy Poplasky, one of the ISS’s first female commanders, to investigate the cause. Russia has just invaded Ukraine and tensions are running high – could the leak be a brazen act of sabotage? The Russian cosmonauts aboard deny tampering with the ship’s systems and insist on the issue stems from the American side. As levels of the poisonous gas rise, Lucy’s investigation shatters trust between the Russian and Western crews, exposing deep fissures in the partnership thousands of miles below.