Her code name is Sparta. Her beauty veils a mysterious past and abilities of superhuman dimension -- the product of advanced biotechnology. Recovering from her mission on Mars in "Venus Prime 3," Sparta finds herself the guest of the Space Board. But relaxation is short-lived as she sets out on an interplanetary investigation -- of the Space Board itself! Members of the Free Spirit, a religious cult intending to gain control of all the worlds of our galaxy, have infiltrated the Space Board. As the date of the manned mission into the clouds of Jupiter approaches, Sparta's suspicions grow. She is certain the mission has fallen into the hands of the cult, and she is determined to stop it.