The Doctor, Ace and Mel are caught in a forever night. After crossing the threshold, a strange world awaits them.
An army of tortured souls. A lift that leads to an alien landscape. An alien warlord, left for dead, and willing to do anything to prolong his life... it's all in a day's work for the Doctor.
But when his companions become victims of the desperate and powerful Arkallax, the Doctor will have to do battle in a psychic environment where he must make a choice. Save his companions... or himself.