The Doctor (Christopher Eccleston), Rose (Billie Piper), and Jack (John Barrowman) are cornered in a London hospital during the Blitz by patients with gasmasks fused to their faces—all asking for “Mummy.” The Doctor pretends to be Mummy and sends them to their room, and the patients shuffle off. Included among them is Jamie (Albert Valentine), the first victim of the alien epidemic, leaving his sister Nancy (Florence Heath) alone.
The Doctor, Rose, and Jack investigate the hospital room were Jamie was treated and learn that the child is growing more powerful and may soon be unstoppable. Suddenly, they realize that Jamie has been sent to his room and that is exactly where they are, when Jamie suddenly appears. Jack transports himself, the Doctor, and Rose to Jack’s cloaked spaceship. The Doctor heals his wound with Jack’s nanogenes, taken from the Chula spaceship that began the epidemic in the first place, while he learns more about Jack’s past in the future.
Nancy returns to the place where the Chula ship landed and is captured by soldiers. The Doctor, Rose, and Jack return to the site and find the guards’ faces transformed into gasmasks. The contagion is now airborne. The Chula medical ship scanned the first human to die there, Jamie. They believed the gasmask was his normal face and restored him to what they thought was life. The transformed humans are coming in a crowd.
The Doctor realizes that Jamie is the template concerning all the victims. He was searching for his mother when he died, and so are all the others. He also realizes that Nancy is not the boy’s sister but his unwed mother and convinces her to identify herself to Jamie. The nanogenes gather about them, determine the genetic truth, and use her DNA as the new template. Everyone, including Jamie, returns to normal life.
A German bomb is coming. Jack returns to his ship, snags the bomb, and steers it away from Earth. The Doctor warns everyone away from the Chula landing site, sets the ship to self-destruct, and restores the timeline. The Doctor rescues Jack from the bomb and he joins the Doctor and Rose in the TARDIS. The Doctor, overjoyed that for once everyone has lived, dances with Rose to In the Mood by Glenn Miller.
The nanogenes were called nanites in the beginning, but that word was used in Star Trek and was changed. Writer Steven Moffat took the line, “Life is just Nature’s way of keeping meat fresh,” from a sitcom he wrote. Jamie’s voice is recorded on tape in the episode, even though magnetic tape recorders had not yet come to England from Germany. Moffat joked that Brigadier Lethbridge-Stewart’s ancestor stole the machine from Europe.
Nobody dies permanently in this episode, which is rare. It tells us that in the 51st Century, humans breed with aliens. Jack’s sonic blaster is from Villengard. The Doctor destroyed the arms factory and replaced it with a banana plantation. The sonic screwdriver can break concrete or reattach barbed wire. The music contained a tune later used in the Torchwood theme. Jack Harkness may have been named for Agatha Harkness, a character in the Fantastic Four comic. Together with The Empty Child, The Doctor Dances won the 2006 Hugo Award.