Sarah Jane Smith and her co-worker Jeremy Fitzoliver are on holiday in Sicily when they meet the Brigadier. The Brigadier is trying to help his Uncle Mario, who is being threatened by a mobster named Vilmio. Mario is also trying to deal with the ghosts that have been sighted in his castello. The Brigadier asks the Doctor to investigate the hauntings and determine their source. The Doctor reveals that the ghosts are "N-Bodies", or the souls of the deceased who have not yet left the physical plane. The ghosts are gathering around Mario's castello due to a fracture in the N-Space barrier; if the barrier were to fail, Earth would be overrun with the monsters that inhabit N-Space. The Doctor travels back to the 19th and 16th century in an attempt to locate the cause of the fracture. In the past he discovers that Vilmio is actually an alchemist called Vilmius who has discovered a method for extending his lifespan; now that he is nearing the 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 novelBusiness Unusual, but when BBC ordered it changed from a Third Doctor to a Sixth Doctor novel, the character was dropped.
The term "N-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.
In Print
Barry Letts' novelisation of the script was released as part of the Virgin Missing Adventures range of spin-off novels in 1995, nearly a year before the broadcast of the serial.
