A runaway asteroid dubbed "The Outsider" mysteriously begins orbiting the Earth and threatens it with lethal flying saucers.

A stray planet on a collision course with Earth instead takes orbit around our blue marble. What seems like a dead planet suddenly launches a fleet of flying saucers which attack our space fleets.—Humberto Amador

Men & women in rocket ships near Mars gasp "Inverting... course... 180... degrees..." in high-gee maneuvers. Meanwhile, the offbeat scientist (Claude Rains) shouts at the labcoats who have invaded his greenhouse (where he spends his time tending flowers and scribbling math in chalk on the pots): "Back you madmen! I have one advantage over all of you! Calculus!" Sine waves and music are eventually used to talk to "the outsider."—David Van Brink <umlaut@echo.com>