The Ghosts of N-Space

The Ghosts of N-Space is a radio drama based on the long-running British science fiction television series "Doctor Who". It was recorded in 1994 and finally broadcast in six parts on BBC Radio 2 from January 20 to February 24, 1996. This was the second Third Doctor radio play, following "The Paradise of Death" in 1993. Plans for subsequent serials were abandoned after the death of Jon Pertwee in May 1996.
The announcer in the radio serial gave the title as "Doctor Who and the Ghosts of N-Space", but both the cassette and CD releases have dropped the "Doctor Who and" prefix in their packaging, as does the novelisation.
It was written by Barry Letts, and featured Jon Pertwee as the Third Doctor, Nicholas Courtney as Brigadier Lethbridge-Stewart and Elisabeth Sladen as Sarah Jane Smith.
The recording was originally released on cassette in 1996, re-released on a three CD set in 2000.
Plot.
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.
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 (the first BBC novelisation to not be published under the Target Books range, which had been retired the previous year).