The Tardis lands on the moon in 2070. The Doctor and his companions put on spacesuits and venture outside. Jamie is injured jumping around on the surface. Workers from the nearby base find him and bring him inside with the rest of the time-travellers. This moon base uses a Gravitron to control weather on Earth. The international staff are suffering from an unknown pathogen, and the moon base is quarantined. The first patient, Doctor Evans (Alan Rowe) dies, ranting about the “silver hand” and another crewman disappears in the food stores. They learn that someone is monitoring their radio transmissions.
In Sickbay, Jamie, in the throes of a fever, rants about the “Phantom Piper” who traditionally appears before a McCrimmon dies. Polly sees some figure leaving through a door. Commander Hobson (Patrick Barr) and the Doctor arrive to collect Evans’ body and discover it is missing. Polly goes for water and Jamie wakes to see the Piper coming for him. It ignores him and takes another patient. Polly returns in time to recognize it as a Cyberman. Hobson is certain that the Cybermen died out ages ago and gives the Doctor 24 hours to learn the cause of the virus or they must leave, then goes off to deal with the Gravitron. Polly and Jamie are stunned with electricity by a Cyberman, who leaves with another body.
The problem with the Gravitron involves some broken antennae on the moon’s surface. The workers sent out to fix them are beaten to death by Cybermen. The Doctor discovers that the virus has purposely been spread through the food stores. The Cybermen recognize the Doctor, confine Ben and Polly in Sickbay, and take over the Gravitron, hoping to destroy life on Earth by controlling the weather. The battle of the moon base crew and the Tardis crew versus the Cybermen begins.
Jamie spent most of the story in Sickbay because it was difficult to write him into the already-finished script. The first and third episodes were lost and subsequently restored with animation. The Cybermen were now well on their way to becoming the second most popular villains after the Daleks. Gone were the sock-puppet bodies, replaced by metallic-looking plastic, and the awkward searchlight-like chest-apparatus became more sleek and robotic-looking. Their sing-song voices became more computer-like. If Star Trek’s Borg were not inspired by the Cybermen, I’ll eat my hat. They assimilate their victims into a collective and like to say, “Resistance is useless.”