The Doctor, an alien time traveller from the planet Gallifrey, is transporting the remains of his nemesis, the Master back to their homeworld. However the Master is not as dead as the Doctor thinks. The Master's essence escapes and sabotages the TARDIS, the Doctor's time machine causing it to crash land in San Franscisco on December 30th 1999. The Doctor requires a beryllium atomic clock to repair the TARDIS, but is shot as he leaves it. Taken to hospital, the Doctor's seventh regeneration is triggered by a surgeon, confused by his alien physiology, while the Master takes over a paramedic's body. He needs a Time Lord's body to survive and be able to regenerate again so he needs the Doctor's. The newly regenerated the Doctor must fight to save his own eighth body, and the world when the Master sabotages the TARDIS' power source. By midnight on December 31st 1999, the Earth will be pulled through this power-source, a mini-black hole, and only the Doctor can stop if only he can remember who he is...