In an
alternate 1973, the United States is preparing to launch Apollo 18, a military mission to the Moon funded by the
Department of Defense. Kazimieras "Kaz" Zemeckis, an
astronaut candidate, grounded after he lost an eye when his
F-4 Phantom jet struck a seagull, supports the mission from the ground, and is the liaison between the Apollo program and the
National Security Agency. Apollo 18 is to be crewed by mission commander Tom Hoffman, Lunar Module pilot Luke Hemming, and command module pilot Michael Esdale. But Tom dies in an unexplained helicopter crash, and backup astronaut Chad Miller takes his place as mission commander. Apollo 18's military objective is to land on the Moon near to
Lunokhod, a Soviet rover, establish what it is doing, and then disable it. But close to Apollo 18's launch, the Americans learn that the Soviets are about to put a military space station,
Almaz, into Earth orbit to spy on the Americans. Apollo 18's mission is changed to first rendezvous with Almaz in orbit, photograph it, disable it, and then continue to the Moon. Apollo 18's military agenda is not revealed to the public. In April 1973, Apollo 18 is launched and it intercepts Almaz, but the crew are surprised to find two
cosmonauts aboard the Soviet station. A battle ensues, and Almaz is destroyed. Luke and one of the cosmonauts are killed, and the other cosmonaut, Svetlana Gromova, is taken aboard Apollo 18. With a crew of two Americans and a Russian, Apollo 18 proceeds to the Moon.
Vladimir Chelomey at Moscow mission control, who has been listening to Apollo 18's communications with Houston, secretly sends messages to Chad and Svetlana in Russian. Chad is a Russian orphan adopted in Berlin as a child after
World War II by an American family. Moscow instructs Chad to retrieve a rock
Lunokhod has found, but Chad gives Svetlana no indication whether he will comply with Moscow or where his loyalties lie. Chad pilots the lunar lander with Svetlana to the surface near
Lunokhod, and the two proceed to the rover on foot. Chad locates and pockets the rock, and then, unbeknown to Svetlana, sabotages the rover by covering its thermal radiator with lunar dust causing it to overheat. Chad and Svetlana return to the command module in orbit around the Moon, and it returns to Earth. Kaz and flight director
Gene Kranz are told that investigations have revealed that Tom's helicopter had been sabotaged, and that Chad may have been responsible. Kaz and Gene begin to question Chad's loyalties to the United States. Kaz is aboard one of the American recovery ships in the
Pacific Ocean waiting for the Apollo 18
splashdown, but Chad changes the capsule's re-entry point away from the American ships and close to a Soviet submarine. Kaz arrives by helicopter a while after splashdown to find Chad and Svetlana fighting in the water over the
Moon rock. Svetlana gets the better of him and escapes with the rock in the submarine. Kaz confronts Chad about his actions, but Chad dies from his injuries. ==Critical reception==