A virus mutated inside the compound and became airborne. Children of the motorway. Everyone? Everything is powered. MARTHA: "You're not alone." Macra! Martha screams and struggles, but they're quick, they retreat, taking Martha with them. NOVICE HAME: My lord gave his life to save the city. Novice Hame is busily turning a wheel next to the Face of Boe. Request access to the fast lane. Save them. Six years? THE DOCTOR: Finding my own way. THE DOCTOR: I've opened the roof of the motorway. THE DOCTOR: It's the Face of Boe. THE DOCTOR: The Macra used to be the scourge of this galaxy. The Doctor runs over to the door in the bottom of the car, using his sonic screwdriver to flip it open. The Doctor turns and dashes over to the Face of Boe, kneeling in front of it as he did in the hospital where they last met. The fast lane. The image on the screen shifts to reveal the New New York above ground, a gorgeous spired city on the coast of a large river, with sleek flying vehicles zooming in the air. They're on the motorway. This is not easy. Was she car-jacked by two people? Year five billion and fifty-three, planet New Earth!
Plan: A: The Doctor; Q: Who takes Martha to the undercity of New New York? A: Martha; Q: Who is kidnapped by two motorists in flying cars? A: the year 5,000,000,053; Q: When does the Doctor take Martha to the undercity of New New York? A: 24 years earlier, a virus; Q: What killed nearly everyone on the planet? A: 24 years earlier; Q: How long ago did a virus kill everyone on New Earth? A: the virus; Q: What was the undercity sealed off to save it from? A: its system; Q: What did the Face of Boe and Novice Hame maintain to keep the undercity sealed off? A: the Face of Boe; Q: Who tells the Doctor he is not alone? A: his nurse; Q: Who is Novice Hame? A: enough power; Q: What did the Face of Boe and Novice Hame lack to reopen the undercity? A: the fast lane; Q: What part of the Motorway is infested by crab-like Macra? A: a way; Q: What does the Doctor find to restore power to the system? A: the roof; Q: What part of the Motorway did the Doctor open? A: the inhabitants; Q: Who is trapped in the undercity's Motorway? Summary: The Doctor takes Martha to the undercity of New New York on the planet New Earth in the year 5,000,000,053. 24 years earlier, a virus mutated which killed nearly everyone on the planet. The undercity was sealed off to save it from the virus, its system being maintained by the Face of Boe and his nurse Novice Hame, but they did not have enough power to reopen it. Martha is kidnapped by two motorists in flying cars to grant them access to the fast lane on the Motorway. The fast lane is infested by crab-like Macra, old enemies of the Doctor and the former rulers of an empire in this galaxy who have since devolved. Aided by the Face of Boe, who uses the last of his life, the Doctor finds a way of restoring power to the system which opens the roof of the Motorway, finally freeing the inhabitants trapped in the undercity's Motorway and saving Martha and her kidnappers from the Macra. Before dying, the Face of Boe tells the Doctor he is not alone.