About: Def-Con 4

Def-Con 4 is a 1985 post-apocalyptic film, portraying three astronauts who survive World War III aboard a space station. Eventually they must return to Earth and try to survive there. Despite this film being about the aftermath of a nuclear war, 'Def-Con 4' actually means "Defense Condition: Normal, with increased intelligence and strengthened security measures", and is only one step above "Peacetime readiness". Def-Con 2 or Def-Con 1 would deal with potential or actual nuclear exchanges.