Geoff Wedgwood (Stewart Guidotti) and Margaret Henderson (Hester Cameron) had been monitoring an object that landed on the surface of Venus. Geoff and Margaret believe that it is the American, Captain Wilson (Graydon Gould). Following where the blip landed, they find Wilson’s abandoned ship. The inside appears to have been ransacked alluding to the culprit being someone or something strong and huge.
When Conway Henderson (Gerald Flood), Professor Mary Meadows (Pamela Barney) and Harcourt Brown (George Coulouris) reach Wilson’s rocket the entire group begins trying to track Wilson’s movements. Ever since they landed, the group felt as if someone or something were watching them. Then Brown disappears.
Brown finds Captain Wilson (Graydon Gould) in the jungle. Brown, who firmly believes there is a Venusian city on the other side of the mountains, convinces Wilson to go with him by telling him that he was the only survivor of MR-4. Wilson and Brown immediately have problems getting along, but since Wilson believes they are the only two people on the planet, he acquiesces to Brown’s overbearing manner.
Henderson and Geoff go searching for Wilson and Brown while Mary and Margaret go back to MR-4. While they are closing the hatch to the control room something breaks into the lower half of the rocket and starts destroying it. They make an emergency call to Henderson and Geoff. Henderson assures them that they are heading back to the rocket. And then Henderson disappears.
The American astronaut, Captain Wilson, is played by Canadian actor, Graydon Gould. Gould was the voice of Mike Mercury, as well as other voices, in the children's television series “Supercar”.