Donna Noble

After parting company with The Doctor, Donna Noble has become disenchanted with normal life and has realised that she made a mistake when she declined The Doctor’s offer to travel with him in the TARDIS. Now she finds herself seeking out every hint of the unusual and the unexplained, in the hope she would find him again.

And so while investigating Adipose Industries, a company which has created a suspiciously successful revolutionary diet pill with the slogan "the fat just walks away", Donna crosses The Doctor’s path – but is not aware of how close she is to him. Together, they attempt to stop the death of thousands of people in London completely unaware of each other’s involvement.

After securing a list of Adipose Industries customers Donna discovers that the head of the company, run by the sinister Miss Foster, is actually using the diet pill to create a breeding ground for the alien Adipose - short white aliens made from human body fat. It seems that the pills use latent body fat to parthenogenetically create the Adipose, which spawn every night, removing a little of the host's body fat each time.

An Adipose

Donna’s plan to become reunited with The Doctor finally succeeds when they spot each other and so their partnership to discover what is happening within Adipose Industries begins. They soon discover that Miss Foster is in fact an alien who is exploiting Britain's overweight population to create the Adipose for the Adiposian First Family.

Millions of people, who have been using the diet pill, are at risk because in an emergency, multiple Adipose can spawn at the same time by using all of the body's organic tissue, so killing the host.

Donna Locates The Doctor

Feeling threatened by The Doctor’s investigations and attempts to ruin her plans Miss Foster accelerates her plans by releasing the Adipose all at the same time. And so throughout London, the Adipose begin to spawn.

The Doctor and Donna prevent total emergency parthenogenesis from occurring by disabling the berthing machine. They then witness the Adipose that have already spawned make their way to Adipose Industries as The Adiposian First Family’s spaceship arrives and start to collect the Adipose.

Thinking that she is about to be rescued Miss Foster follows them in the tractor beam but despite The Doctor’s warnings is killed when Adiposian First Family hide any evidence they used Earth illegally.

The Doctor

Unknown to Donna the woman is Rose Tyler - a former companion to The Doctor. As Rose walks away from the area she fades away.

With Earth safe The Doctor returns to his TARDIS and Donna discovers that she had parked her mother’s car in the same alleyway. After accepting his offer to travel in the TARDIS Donna makes a detour to leave her car keys in a safe location for her mother Sylvia and so asks a blonde woman to help Sylvia find the keys.