The British rocket ship MR-4 was originally scheduled to land on the Moon.  The crew consisted of replacement pilot, Conway Henderson (Gerald Flood), Professor Mary Meadows (Pamela Barney), young Geoff Wedgwood (Stuart Guidotti), and Henderson’s teenaged niece, Margaret Henderson (Hester Cameron).  The fifth member of the crew is Harcourt Brown (George Coulouris).  Also on board is Hamlet, the guinea pig. 

Brown is a science fiction writer and part of a fringe element that believes Mars and Venus are inhabited.  Brown posed as the scientist originally scheduled to be on the flight.  Brown high jacked the ship and diverted it to Mars, endangering everyone on board.  Eventually, with the help of the crew at the Buchan Island Rocket Research Station, the ship was put back on a course to Earth. 

About three days out from Earth the crew of MR-4 receives an S.O.S. coming from Venus.  They make radio contact with an American, Captain Wilson (Graydon Gould).  Wilson was on a top-secret mission to Venus when he was hit by a meteor that damaged his spaceship.  He is orbiting Venus and is running out of air and fuel.  Through contact with Buchan Island and the Americans, MR-4 learns that a Russian spaceship is sending supplies and oxygen to the American ship, but it will take some time to get there, and Captain Wilson will run out of air before then.  MR-4 is sent to rendezvous with the American ship and provide assistance until the Russian ship arrives.

The crew of MR-4 has a problem with the same runaway comet that incapacitated the American ship.  They managed to find a way to outmaneuver it.  The rest of the trip goes smoothly until they reach Venus.  A message from Captain Wilson says that he is having problems with his ship.  He is going to make adjustments but if they don’t work, he may have to land on Venus.  Brown takes the opportunity to adjust the tape recording of his message to make it sound as if he’s already landed on the planet.  His con convinces Henderson that they also must land in order to save Captain Wilson.  His manipulation will put the rest of the crew in jeopardy.        

“Pathfinders to Venus” was released in 1961.  It is the third and last of the Pathfinder series and the fourth of the space films written by Malcolm Hulke and Eric Paice and produced by Sydney Newman.  It is a direct sequel to “Pathfinders to Mars”.