The Doctor (David Tennant) is shocked when Donna Noble (Catherine Tate) appears in the TARDIS. He returns her to her wedding. At the reception, he figures out that she must have absorbed a massive dose of huon particles to have been drawn into the TARDIS that way. The reception is attacked by Santa Claus robots. The Doctor manipulates the sound system with the sonic screwdriver and destroys them, but something is controlling them.
He learns that Donna and her fiancé Lance Bennett (Don Gilet) work for a locksmith company owned by the Torchwood Institute. He asks Lance to take them there and finds a tunnel beneath the building that runs beneath the Thames Barrier to a secret lab that produces huon particles, and a pit that leads to the centre of the Earth.
The Empress of the Racnoss (Sarah Parish), a kind of giant spider, had been hiding in hibernation at the edge of the universe. She awoke and used Torchwood to secure the equipment to make huon particles. Lance admits that he fed these particles to Donna in her coffee on behalf of the Empress, to help her free the spidey children. Donna and the Doctor escape, so the Empress uses Lance, feeding him the particles and throwing him into the pit.
The Doctor takes Donna back into the TARDIS and travels back billions of years to discover the Racnoss ship around which the Earth formed. The Empress is now trying to wake her children aboard the ship using those huon particles. The Doctor and Donna return to the present as the spidery offspring begin to emerge from the pit.
The Empress refuses The Doctor’s peaceful solution, and he is forced to detonate the explosive Santas, flooding the pit with the River Thames. Donna Noble urges him to escape with her, as the Empress teleports to her ship. However, its defenses are much weakened, and the ship is destroyed. Donna refuses to travel with him, but says he needs a companion to keep his temperament in check.
A scene filled with a blizzard of money was made with banknotes with the Doctor’s face on them. Catherine Tate was unable to be at the readthrough and Donna Noble was read by Sophia Myles, Madame de Pompadour in the Girl in the Fireplace and David Tennant’s girlfriend. Donna Noble would return in Season Four as a full-time companion. The episode was well-received generally, the sillier parts considered acceptable in a Christmas Special. A double-decker bus passing by bore an ad for Hedrik’s Department Store, where Rose Tyler had worked.
It took four hours in makeup to transform Sarah Parish into the Empress of the Racnoss. This was the episode in which the TARDIS pursues a car down the highway, which Russel T. Davies had wanted to see since he was a kid. Like most people, I found Donna Noble highly irritating at first, a distraction from the Doctor’s general heartbreak on losing Rose. But by the end, I was able to find a kind of wisdom in her. Then, when she returned later, after Freema Agyeman as Martha Jones served as companion, she really grew on me until she became one of my favorite companions. She never let the Doctor get away with anything, and in the end Donna Noble turned out to be damned noble, with one of the best, most touching and beautiful companion departures ever.