[1] A spy discovers that the Chinese government has created a doomsday device (the "key" to which, "only Chairman Mao has") capable of destroying the Earth and it will be activated in 72 hours.

Soon after, Astra – a two-year return mission to Venus by the United States Space Program – has its time of launch speeded up and half of the male flight crew are replaced by women shortly before take-off, including one Russian.

It gives a cryptic message regarding the prospect of starting new life in a "very strange and very great" place, somewhere far "beyond the rim of the universe," before the ship suddenly blasts off, apparently by the power of the Venusians, and the movie abruptly concludes.

The film relies extensively on stock footage, including real (but badly degraded) NASA rocket footage, special effects shots from David L. Hewitt's The Wizard of Mars (1965; Hewitt receives a special effects credit for Doomsday Machine), Gorath (1962) and other disparate sources, leading to numerous continuity errors.

The protracted last segment of the movie – with an American and Russian astronaut boarding a derelict Soviet spacecraft – was obviously shot after the unfinished principal photography without the participation of the original actors.