After chasing an unexplained capsule through time, the TARDIS lands in London, during an air raid. Rose investigates when a small child wearing a gasmask, standing on a rooftop, continuously calls out for his mummy. After floating above the city on a barrage balloon, Rose is swept off her feet by another time traveller – Captain Jack Harkness. Meanwhile, The Doctor follows a teenaged girl to a meeting of the homeless children of the Blitz. Here, the child in the gasmask is terrorising them with a parade of strange events, constantly asking for his mother.

After narrowly escaping the gas mask monsters, The Doctor, Rose, and Captain Jack try to stop the mutated people from infecting other victims. But it soon becomes apparent that one of the group may indirectly responsible for the virus. The answer lies at the bomb site, but time is running out...

Rose and the newly-regenerated Doctor continue their adventures together in this Christmas Special episode. Christmas becomes a time of terror for Planet Earth, as the whole of mankind falls under the shadow of the alien Sycorax. Rose needs the Doctor's help, but can she trust a man with a new face?

In the year five billion and twenty-three, after the destruction of the Earth, the Doctor takes Rose to the New Earth. There, in a hospital facility, the feline Sisters of Plenitude can mysteriously cure any diseases, but, in the basement, an old enemy of the Doctor is out for revenge.

There are strange goings-on at a comprehensive school - UFOs, over-intelligent children, and odd-tasting school dinners. This attracts the attention of the Tenth Doctor, Rose and Mickey Smith, as well as a couple of old friends…