Young scientist, Mark Curio, plots a secret mission to save doomed planet, Anthros, which is in the direct path of a giant killer meteor. His hand-picked Earth crew and King Ut of Anthros, plus a handful of Ut's people, endeavor to transplant that civilization to little-known planet, Braun.
Braun will sustain life; however the life that now occupies it, is all male, having created an imbalance of the sexes while genetically trying to subdue their population. The female gender only gives birth to females after Dr. Abor administers his serum, and forces them to live in the sea. They begin reproducing without males and continue to spawn only female offspring. These "she-mutts" are vicious creatures that have become cannibalistic, as well.
When the visitors from planets Earth and Anthros arrive, Nile, the leader, stakes claim to the females on board, thinking that a mixed breed would produce a son to be the new king of his planet, which he calls, Mirabus.