The TARDIS lands in London on a parallel Earth. It’s damaged extensively, with only a small power cell still functioning. The Doctor (David Tennant) energises the cell with his own lifeforce. But the time-travellers have to wait 24 hours before they can leave. On this Earth, Rose’s (Billie Piper) father, Pete (Shaun Dingwall), is still alive. She sees a billboard with his picture on it. Mickey (Noel Clarke) heads off to find his beloved grandmother. On his Earth, she died a few years earlier in an accident. The Doctor and Rose discover that most of the people in London wear earpods that feed information directly into their brains, produced by Cybus Industries, which owns Pete’s company Vitex.

The head of Cybus Industries, John Lumic (Roger Lloyd-Pack) is trying to get the President of Great Britain (Don Warrington) to approve his plan to upgrade humanity by placing their brains into metal exoskeletons. Secretly, Lumic has already turned a number of homeless people into Cybermen. A group called the Preachers is investigating him. One of them, Jake Simmons (Andrew Hayden-Smith), sees a group of homeless being taken away and goes to get help. Jake finds Mickey at his grandmother’s house and thinks it’s Rickey. He takes him to the Preachers’ base, where Mickey and Rickey meet. Mickey decides to join the Preachers in following the Cybus vans, which go to Pete’s wife Jackie’s (Camille Coduri) birthday party.

Rose and the Doctor show up as well and dress as servants to investigate. Cybermen smash into the house and surround the guests. Lumic calls the President, telling him he is going to upgrade all of humanity. A Cyberman kills the President for refusing to comply, citing him as not compatible. The partygoers panic and flee and are surrounded by Cybermen. The Doctor stalls for time by telling everyone to surrender, but the Cybermen pronounce them incompatible and say they will be deleted. To be continued.

The Cyberman army is chilling, stomping in lockstep with steel boots on pavement. Finally, there is a big enough budget to do this sort of thing. The story is based on an audio play called Spare Parts and there are a few nods to this. Early drafts featured body shops where wealthy patrons would purchase replacement limbs, but this was thought far-fetched (!). Jackie’s 40th birthday party is a nod to The Tenth Planet episode in which the Cybermen first appeared. We have come a long way from the sock-puppet-like creatures with the huge cameras on their chests. The Art Deco style of the Cybermen is terrifyingly industrial. The episode ends with to be continued for the first time in the Doctor Who series. There had been criticism of the episode Aliens of London, which ended with spoilers of the next episode. Graeme Harper is the first director to direct stories in both the original and new series.

Roger Lloyd-Pack and David Tennant had worked together in Harry Potter and the Goblet of Fire, playing Barty Crouch and his son. Lloyd-Pack broke his leg days before filming, but he was supposed to play the role in a wheelchair anyway. His character was based on Donald Rumsfeld. The teardrop design of the Cybermen’s eyeholes returns here and will remain. It adds just a bit of commentary on the sad fate of those who are upgraded. Alternate universe stories are rare in Doctor Who, but there were several in the Doctor Who novels. According to the Doctor, the Fall of Gallifrey means such crossings are almost impossible. Torchwood exists in this universe, but Rose does not, except as Jackie’s Yorkshire Terrier, but somehow everyone relates to her. Lumic in the wheelchair and his Cybermen are reminiscent of Davros and his Daleks.