The Doctor’s alone, but he’s defeated the Master and is in relatively lighter spirits. He’s about to leave Earth again (after a short conversation with his fifth incarnation) when suddenly the TARDIS is rammed by a giant ship-the Titanic.
Repairing the damage, the Doctor discovers it’s actually a space Titanic for space tourists, on a Christmas voyage,.
Unfortunately, the ship seems doomed to meet the fate of it’s namesake, as the ship’s captain allows the ship to be hit by meteors. What’s worse, the robot “angels” on board have also gone berserk, and the ship is heading on a collison course with Earth.
The Doctor gathers the survivors together (including maid Astrid played by singer Kylie Minoque) and asks them to follow his lead. His reasoning:
I’m the Doctor. I’m a Time Lord. I’m from the planet Gallifrey in the constellation of Kasterborous. I am 903 years old and I’m the man who’s gonna save your lives, and all six billion people on the planet below. You got a problem with that?
The Doctor is able to eventually steer the Titanic out of a collision with London, meeting this guy along the way:
Wilfred “Wilf” Mott, who will become important very shortly.
Unfortunately, during the adventure, Astrid falls to her death, and the Doctor is unable to save her. Turns out the whole thing was an attempt by the guy who created the cruise in the first place, as a way to bankrupt his own company.
The Doctor’s next adventure takes him back to present-day London, where he once again meets Donna, who has been looking for him. It also turns out Wilf is her grandfather.
The two team up and find out that a new diet pill that is being marketing is turning people who take it into tiny, cute colonies of small aliens known as “Adipose”. The Doctor stops the pill, but lets the aliens go, seeing as they’re really just kids:
Donna decides to become the Doctor’s new companion, although neither are interested in any romance. Meanwhile, just before she leaves-Donna drops her keys off, telling a young woman to tell her mom to find them.
The woman turns:
Looks a bit familiar doesn’t she? Rose Tyler is back in ‘our’ universe, but time will tell just how, and why, and when she’ll cross paths with the Doctor again.