After having successfully piloted the supply ship out of the Earth’s atmosphere, Henderson (Gerald Flood), Geoffrey (Stewart Guidotti) and Jimmy (Richard Dean) find out that someone has stowed away on the ship. The stowaway turns out to be the boys’ sister Valerie (Gillian Ferguson). It’s too late to turn around and bring her back so Valerie is now the fourth member of the team.
When Professor Wedgwood (Peter Williams) finds out that his three children are on another rocket heading for the moon he is not happy. The Professor orders them to orbit the Earth but Jimmy points out that it would be safer for them to orbit the moon since they don’t have to worry about hitting an atmosphere and burning up. Professor Wedgwood concedes and allows them to continue.
Once they reach the moon Dr. O’Connell (Harold Goldblatt) becomes unstable and refuses to let the spaceship land. He is eventually overcome and the ship lands on the moon’s surface successfully. O’Connell, now back in his right mind apologizes for his panic attack.
Wedgwood’s team no soon lands when they observe the supply ship coming from a different direction. Henderson and the kids on the supply ship think that the first spaceship is still in orbit. It takes a little while before both ships realize that what they are observing on radar is a third ship. An unknown alien ship is orbiting the moon.
The Pathfinders series was written by Malcolm Hulke and Eric Paice. Hulke would go on to write several of the “The Avengers” and “Dr. Who” episodes, specifically “Invasion of the Dinosaurs”. Eric Paice also wrote episodes for “The Avengers”.
The series, as well as its sequels “The Pathfinders to Venus” and “The Pathfinders to Mars” were written specifically for children as not only an entertaining series but as an educational forum as well.