end of his life, he wants to use the power of N-Space to give himself true immortality. He also plans to control the monsters in N-Space and use them to rule the world. Vilmius has been waiting centuries for a specific astrological conjunction to occur, which is scheduled to occur in the next few days. Vilmius' men storm the castello, allowing Vilmio access to the N-Space fracture. The Doctor and Sarah Jane, using a device the Doctor invented, send their N-bodies into the fracture as well. Inside N-Space, Sarah Jane's belief in the Doctor transforms his body into that of a heroic white knight, which allows the Doctor to defeat Vilmius and sever his N-Body's link with his physical body. The defeat comes too late, and Vilmius begins absorbing the N-Space energy into his body. In a last-ditch attempt, the Doctor increases the amount of N-Space energy funnelling into Vilmius, which causes him to explode; the N-Space energy disperses harmlessly. Continuity Jeremy Fitzoliver was introduced in Barry Letts' first Doctor Who radio play, The Paradise of Death and went on to appear in Letts' Past Doctor Adventure novel Island of Death. He is also featured in the Past Doctor Adventures novel Instruments of Darkness. Author Gary Russell originally intended Fitzoliver to be a part of the novel Business Unusual, but when BBC ordered it changed from a Third Doctor to a Sixth Doctor novel, the character was dropped. The term "N-Space" (Null Space) here is used differently than it is during the E-Space trilogy, where it stands for "Normal Space." Sarah Jane mentions encountering the Daleks, placing this story after Death to the Daleks. The Doctor tells Sarah Jane a story about hiking around Gallifrey with a wise teacher who lived in the mountains. This seems to be a reference to the Gallifreyan they encounter in Planet of the Spiders. Cast and Crew Notes Broadcast a few months before his death, this was Jon Pertwee's final performance as the Doctor. Sandra Dickinson was married to Peter Davison (The Fifth Doctor). Their daughter, Georgia Tennant, played Jenny in The Doctor's Daughter, and later married David Tennant, the Tenth Doctor. Stephen Thorne appeared in The Dæmons, The Three Doctors, Frontier in Space and The Hand of Fear. Harry Towb appeared in The Seeds of Death and Terror of the Autons. In Print Barry Letts' novelisation of the script was released as part