Doctor Who - Target Novelisations - 076 - Castrovalva

The Master leaned back, permitting himself a thin chuckle that floated away into a whisper. 'Oh no, you can't escape. You're mine, Adric, mine — until we have completed our final task...'

The TARDIS, controlled by the Master, is rushing towards Event One and imminent destruction; Adric and his computational powers are being manipulated to the Master's own ends.

But the Doctor has been weakened by regeneration and the travellers attempt to travel to peaceful Castrovalva unaware of the web that has been spun by the renegade Time Lord...