Def-Con 4 is a 1985 Canadian post-apocalyptic film, portraying three astronauts who survive World War III aboard a space station and return to Earth to find greatly changed circumstances.

Day 407 of the Nemesis Mission as three astronauts man a secret space station armed with nuclear weapons.

Cecil Howe (Tim Choate) receives a broadcast from his wife whose rural community escaped the initial bombing.

Unable to respond, he listens as his wife describes how many residents, including his sister, were blinded by the nuclear explosion.

Two months later, the spacecraft's guidance system is mysteriously reprogrammed, forcing the crew's return to Earth.

Hearing knocking on the capsule, Howe and Walker (John Walsch) attempt to dig out believing they have been found by survivors.

He soon encounters Vincent "Vinny" Mckinnon (Maury Chaykin), a survivalist who has fortified his house with barbed wire and booby-traps.

Using an armor-plated tractor, the group heads back to the beach to find the capsule but are ambushed by survivors from a nearby military fort.

Using satellite equipment taken from the helicopter, it was Boomer who was able to force Howe's space station to crash at the beach.

By using equipment from the salvaged capsule, Gideon finds an active survival station to seek shelter from the radiation and fallout covering the globe.

[4] Kim Newman found the plot of a pre-apocalyptic person thrust into a post-apocalyptic world to be a cliché based on The Time Machine by H. G.