Russia, 1983 - Cold War tensions at their peak. A terrifying scene is discovered at the landing site of spacecraft Orbit-4. The commander is dead, the flight engineer in coma. The third crew member, Valery Basov, has survived, but he has lost his memory. In a secluded government facility, psychologist Tatiana Klimova must cure the astronaut's amnesia and unravel the mystery. In the process, she learns that Orbit-4 may have carried back an alien parasite that threatens to consume them all.