After being in flight for a day and a half the staff at the Buchan Island Rocket Research Station discovers that Professor Hawkins is not on board the spacecraft that is currently headed for the Moon. The ship captain, Conway Henderson (Gerald Flood) and the rest of his crew are unaware that they have an imposter on board.
At the Buchan Island control room, Ian Murray (Hugh Evans), the real Professor Hawkins (Bernard Horsfall), John Field (Astor Sklair), and the rest of the Buchan Island researchers, deduce that the imposter is actually Harcourt Brown (George Coulouris), a fanatical science fiction writer who believes there is life on Mars and Venus. When Buchan Island tries to contact the ship to let them know of the switch, Brown sabotages the radio.
Before landing on the Moon, the team must rendezvous with a supply satellite that is currently orbiting the Moon. After they have picked up their supplies they plan on landing in the Sea of Tranquility. Connecting with the supply satellite will prove to be tricky without the assistance of Earth guiding them. After some maneuvering they manage to couple with the supply satellite. It is then when Harcourt Brown reveals himself and highjacks the ship. His destination, Mars.
Producer Sydney Newman left ABC in 1962. He then joined BBC Television and was made Head of Drama. In 1963 he created Doctor Who, along with Donald Wilson. Michael Craze, who played Geoffrey Wedgewood in the lost “Target Luna” series went on to play Ben Jackson, one of Doctor Who’s companions in the First and Second Doctor series. Gerald Flood, who plays Conway Henderson, provided the voice of Kamelion in the Fifth Doctor Who series.