The best Maurice Denham’s science fiction movies

The inhabitants of Ganymede need to find mates from another world or they will become extinct. They soon discover a suitable breeding stock amongst the females of planet Earth.

A secret jet aircraft capable of traveling three times the speed of sound is being developed by a group of scientists secretly. On the day of the test flight, one of the scientists dies in a mysterious accident, and there are many arguments concerning the flight itself; some think it should be ground-controlled while Heathley (James Donald) wants it to be a manned flight with himself at the controls. Conflict also arises when one of his fellow scientists, taking advantage of Heathley's lack of attention toward his wife, Lydia (Phyllis Calvert), makes some moves on her. Then there is the question of just who is the enemy agent on the project. The single-minded Heathly, much to his dismay and little to his credit, uncovers him when he chooses his co-pilot.

A race of giant Gastropods has taken over the planet Jaconda. Their leader, Mestor, now intends to cause an enormous explosion in order to spread his people's eggs throughout the galaxy, and he kidnaps juvenile twin geniuses from Earth to work out the necessary mathematical equations. Space fighters led by Lieutenant Hugo Lang are dispatched to get the twins back, but they come under attack and Lang is the sole survivor when his ship crashes on the asteroid Titan III. A newly regenerated Doctor and Peri become involved and help Jaconda's elderly former ruler Professor Edgeworth, who is really a Time Lord named Azmael, to defeat Mestor and free the planet's bird-like indigenous people from the gastropods' reign of terror. Azmael, however, sacrifices his life in the process.