Christmas on a Rational Planet is an original novel written by Lawrence Miles and based on the long-running British science fiction television series Doctor Who.

It also contains the first casual reference to the Faction Paradox, which become an important element in the BBC books Eighth Doctor Adventures and subsequent spin-off series, and an explicit explanation that the mark carried by the Third Doctor during his exile on Earth was a branding used to distinguish criminals by the Time Lords (in reality, this mark was a tattoo of a cobra that Jon Pertwee picked up while serving in the Royal Navy).

Europe is recovering from the Age of Reason, the Vatican is learning to live with Napoleon, and America is celebrating a new era of independence.

Secret societies are crawling from the woodwork, and there's a Satanic conspiracy around every corner.

Roz Forrester is stranded in a town where festive cheer and random violence go hand-in-hand.