When his crew is brutally murdered on a Mars expedition, Commander Caruthers becomes the prime suspect. Taken into custody and facing a court-martial back on Earth, he discovers that the real killer — a grotesque, slithering monster — has stowed aboard the earthbound ship. But the creature has already begun a harrowing in-flight rampage, knocking off the members of the crew one by one. Now, as the spaceship heads home toward a panic-stricken Earth, the remaining crew must find some way to stop the monster. Stars familiar 50s Scifi actor Marshall Thompson. Also starring Shawn Smith and Kim Spalding. Jerome Bixby wrote the screenplay. Directed by Edward L. Cahn and produced by Robert E. Kent. Click for other version of poster