Rose stares, stunned, as the young man who has replaced the Doctor sets the TARDIS in flight towards the planet Barcelona on Tuesday, October 5006. He then begins to poke and prod his face and torso, checking out his new body’s attributes: a slight weakness in the right wrist, sideburns, bad skin, and a mole between his shoulder blades. When he turns to Rose for her opinion, she demands that he send the Doctor back, convinced that he’s an impostor -- but he claims that he is the Doctor, even though he just changed every cell in his body to save his life. To prove it, he takes her hand and reminds her of the first word he spoke to her, in a cellar, surrounded by malevolent shop-window dummies: “Run.”

Rose, shaken, asks if the Doctor can change back. He tells her that he can’t, and, realising she’s deeply upset, asks if she’d prefer to go home now. He resets the co-ordinates for the Powell Estate on 24 December, but when he cracks a joke about her mum’s holiday cooking, she smiles, despite herself. But just as it seems that he’s starting to win her over, he convulses and coughs out a cloud of glowing yellow light. Worried, Rose asks the Doctor to go back and fetch Captain Jack to help, but the Doctor insists that Jack is busy enough rebuilding the Earth. His is then distracted by a shiny switch switch on the console, and when he flips it, the TARDIS begins to accelerate. With a burst of manic energy, the Doctor begins to push his ship to go even faster, and in a moment of lucidity, he tells Rose that the regeneration is going wrong. The TARDIS cloister bell begins to toll, and the Doctor gleefully tells Rose that they’re about to crash-land. Next stop, Christmas Eve -- but possibly not in one piece...