Snatched out of time and place and brought before the Time Lords of Gallifrey, the Doctor is on trial for his life.

While the Doctor asserts that the evidence of the Matrix, the repository of all Time Lord knowledge, has been tampered with, the mysterious and vengeful prosecuting council, the Valeyard, is confident that the Doctor will be sentenced to death.

In a dramatic intervention the Valeyard's true identity is revealed but he escapes from the Courtroom into the Matrix, and it is into this nightmare world that the Doctor must follow — to face his ultimate foe...

Novelization of the Doctor Who TV series; parts thirteen and fourteen of the fourteen episode story "The Trail of a Time Lord" (1986), script by Robert Holmes (13) and Pip & Jane Baker (14).