All of Earth's manned missions to Mars have failed to reach the red planet and the ships have been mysteriously lost. Four daring astronauts go to find out why. Four daring astronauts find X, which is actually called Guilala, probably because in kaijū history names that begin with G have been profitable.
There's a lot of filler in the film. It's not until half of the running time has passed, almost exactly, that the creature appears in all his rubber-suited glory. And when he does arrive it's with no surprises in tow.