George Pal's now-quaint science fiction odyssey concerns a multi-national group on the first space flight to Mars. Pal pulls out all stops in the special effects department, creating "The Wheel" (a earth-orbiting circular space station), rocket launches into space, and a breathtaking near-collision with an asteroid. The film itself concerns the travails of the crew of the spaceship as they make their way to Mars. General Samuel T. Merritt (Walter Brooke) heads the team. Supporting him and along for the ride are his son, Captain Barney Merritt (Eric Fleming), Sergeant Mahony (Mickey Shaughnessy), Jackie Siegle (Phil Foster), and Imoto (Benson Fong). As the ship gets closer to their Martian quest, General Merritt cracks and tries to sabotage both the mission and the crew, babbling about the blasphemy of mankind trespassing upon God's domain. His son is forced to kill him and save the mission, whereupon the crew peacefully lands on the Martian surface and scouts out the terrain like a group of sightseers at Lourdes before returning to Earth.