An Australian man is spending Christmas with his ex-wife's in-laws, Jim and Lucy, because his home has been destroyed by the wildfires that now threaten Jim and Lucy's home. Help is on the way, but it becomes increasingly clear that it won't arrive in time.
A man who calls himself the Doctor has arrived to help out. He arranges a complicated contraption and enlists the help of the man and his ex-relations. As the fires get closer, the man's bitterness at his divorce and ruined home threaten to get the better of him, but he benefits from a pep talk by the Doctor.
When the fires arrive, the Doctor's contraption has created a firebreak of ice around Jim and Lucy's home. The fire helicopters arrive, but as they aren't needed, they head elsewhere.
As the man talks to Jim and Lucy, they all realise that none of them knew who the Doctor was, and he has left before they can ask him.
- This story is narrated by Sarah's ex, whose name is never spoken by his former in-laws or the Doctor.
- The Doctor recalls how his own people once allowed a firestorm to destroy a whole world. (TV: The Ultimate Foe)