What appears to be a deserted derelict spaceship crashes into an orbiting space station named Theta that Buck and Wilma are on. Buck checks out the ship and finds the remains of the crew, whom he learns were killed by a vampire-like creature known as the Vorvon (Nicholas Hormann). Buck doesn't realize that the Vorvon is still present until personnel aboard the space station - including Wilma - begin to be taken over by the strange creature, who can control the wills of other beings.