The Doctor (David Tennant) is experiencing side effects from his regeneration. He crashes the TARDIS in London and stumbles out through the door, followed by Rose Tyler (Billie Piper). Alerted by the TARDIS bouncing off the nearby buildings, Rose’s mother Jackie (Camille Coduri) and boyfriend Mickey Smith (Noel Clarke) run to greet them. Once Rose explains that this is the same Doctor in a different body, they take him into Jackie’s flat and put him to bed. He tells them something has gone wrong with his regeneration and he is attracting an old enemy. Then he passes out again.

Guinevere One, the Mars space probe, is seized by a giant spaceship, live on TV. The face of a Sycorax appears and demands that the planet Earth surrender to them. A third of the planet’s population goes into a hypnotic state. These people will commit suicide unless half the population becomes slaves to the Sycorax. The Prime Minister, Harriet Jones (Penelope Wilton), attempts to negotiate and is teleported aboard the ship.

Rose and Mickey go Christmas shopping and are attacked by evil masked Santa Clauses with deadly musical instruments. They rush home and find the flat invaded by a Christmas tree which spins around with razor-sharp branches while playing Jingle Bells. Rose props up the Doctor and puts the sonic screwdriver in his hand to disintegrate the tree.

They bring the Doctor into the TARDIS as the ship nears London, and it is teleported onto the ship. The Doctor recovers from his regeneration trauma with a dose of good English tea and challenges the Sycorax leader to a duel for Earth. The Doctor’s hand is cut off, but he is still within the 15-hour regeneration cycle (who knew?) and it grows back. He defeats the leader and drops him to his death off the ship.

He orders the Sycorax invaders to leave Earth and never return, then takes Rose, Mickey, and Jackie home. The Prime Minister orders Torchwood to destroy the ship as it leaves, enraging the Doctor, but she reminds him that he is not always there to save them. The Doctor tells her he can bring down her government with six words, then whispers to her Aide, “Don’t you think she looks tired?” He chooses his new outfit—a snappy pinstripe suit and a brown duster—then joins Rose, Jackie, and Mickey for Christmas dinner. They watch the Prime Minister on TV, fending off rumours about her health.

This is the first reference to Torchwood, the spinoff to Doctor Who that debuted that year. The two series intersect now and then, but most of the time run separately. I will review Torchwood later. David Tennant wished to be referred to as The Doctor and not as Doctor Who. Peter Davison did the same when he took over from Tom Baker. The BBC launched a fictional website for the Guinevere One space probe, complete with an introduction from the fictional Prime Minister Harriet Jones. The episode features songs written by Doctor Who composer Murray Gold. Other Christmas Specials did the same. This was the first time a TV drama was allowed to film on top of the Tower of London. Among the clothing in the TARDIS wardrobe is a Hogwarts uniform. Sycorax is the name of the witch in Shakespeare’s The Tempest.

The duel with the Sycorax leader will remind you of the light-sabre duel between Luke Skywalker and Darth Vader. Construction girders surround the Big Ben tower, as the damage done by the Slithereen spaceship in Aliens of London is being repaired. Bill Nighy was considered for the role of the Tenth Doctor. The Doctor refers to the pyjamas and bathrobe that Jackie has given him as, “very Arthur Dent.” When Jackie finds out the Doctor has two hearts, she asks, “Anything else he’s got two of?” a line spoken by Arthur Dent about the two-headed Zaphod Beeblebrox in Hitchhiker’s Guide to the Galaxy. The regenerative energy that allows the Doctor to grow a new hand may explain why Romana was able to change bodies so often in Destiny of the Daleks. The Doctor’s severed hand will reappear later several times, after it is retrieved by Captain Jack Harkness.