The Algebra of Ice (novel)

Publisher's Summary
A genius maths nerd, a weird webzine publisher, and the Doctor's old ally, the Brigadier find themselves helping the Doctor and Ace solve what should be a simple puzzle: the appearance of a crop circle in the Kentish countryside.

Hardly uncommon. But there are some peculiar features. It's not a circle but a series of square-sided shapes. It's filled with ice. And it draws the Doctor and Ace into a confrontation with a reality right next to zero.

Characters

 * The Doctor
 * Ace
 * Brigadier Lethbridge-Stewart

Continuity

 * The Doctor destroyed Skaro in DW: Remembrance of the Daleks, but also mentions he hasn't destroyed his own homeworld...this foreshadows EDA: The Ancestor Cell.

Timeline

 * The Algebra of Ice occurs after: PDA: Loving the Alien
 * The Algebra of Ice occurs before: PDA: Atom Bomb Blues