A spaceship is sent to Mars after an alien distress signal is picked up. They find one survivor, but when a crew member is found drained of blood it's evident they have rescued a bloodsucking monster. Uses footage from Encounter in Space (1963).
The terrible and trecherous Pendragon plans to gain the throne of Cornwall by getting the king to abdicate and to marry his lovely daughter. To help him he has his dreadful witches in his castle and his almost unstoppable sorcery. A giant under his control abducts the princess, but on the way home with her the giant meets farming lad Jack who slays him. This is only the beginning.
