This novel provides the departure scene for the companion Liz Shaw. In the television series her final appearance was in the last episode of Inferno, but she is not seen to leave the Doctor. In the Terror of the Autons her departure was announced by the Brigadier.
The novel is also designed as a prequel to the events of the television serial Warriors of the Deep. Specifically, this story explains how the Doctor knows Icthar and how he knows of the Triad and the Myrka.