Space Monster is the 9th Produced episode and the 11th Broadcast episode of the series Fireball XL5.
Fireball XL2 has disappeared and the crew of XL5 are sent to find it. They receive a distress call from the planet Monotane, where Steve Zodiac and Venus, landing in Fireball Junior, find the wreckage of XL2.
A storm forces them into a cave where they find the crew of the destroyed ship, who tell them a monster caused the crash and is now outside the cave. Professor Matic lands in Fireball XL5 and is also forced into the cave. Steve tries to escape but it is up to Zoonie to save the day by imitating the sound of the monster.