Peter Davison (The Doctor), Sarah Sutton (Nyssa), Susan Penhaligon (Shayla), Stephen Greif (Kwundaar), Ian Hallard (Sabian), Romy Tennant (Anona), Rita Davies (Janneus), Mark Woolgar (Hyrca), Billy Miller (Narthex / Captain Kabe), Alistair Lock (Etrayk)

Part One. After Nyssa becomes gravely ill he takes her into Traken's past where medic Shayla stabilises her condition. The Doctor explains that Nyssa's travels with him have led to her exposure to danger and evil, despite his good intentions. The Source is reluctant to advise Consuls Hyrca and Janneus, and they meet with the Doctor and Shayla, who believe the exposure to evil has corroded Nyssa's soul. On the fleet orbiting close to the Union of Traken, Kwundaar, the Living God, awaits. Nyssa explains to the Doctor that these are the primeval times of Traken when the Source governed itself. Kwundaar believes his agent will soon bring the walls of paradise down. Shayla informs the Doctor that the Consuls want him gone and when Nyssa suffers a relapse, Shayla believes Kwundaar might be the only alternative. The Doctor and Shayla travel via a merchant vessel to Kwundaar's fleet, only to be captured. The Doctor tries to bargain with Kwundaar for Nyssa's life, but when he looks at him, the Doctor screams in absolute terror…

Part Two. Shayla and Narthex find the Doctor alive and he explains that Kwundaar is a powerful telepath and he had to push hard to breech his Time Lord defences, but they eventually negotiated and Kwundaar convinced him Nyssa could be cured. The Consuls conclude Nyssa is a cause of peril and must be disintegrated for the sake of Traken, which causes her to collapse again. Shayla's assistant, Sabian, takes Nyssa to a healing spring near the Source. Kwundaar tells the Doctor he wants something from the Source Interface vault. He wants Shayla to remain onboard, but she and the Doctor manage to escape onboard the merchant ship. Nyssa cannot explain her sudden revival, but is quarantined by the Consuls. Kwundaar admits to Narthex that he used Nyssa to bring her here, but she is not his agent. The Doctor fulfils that role. Once he has handed Kwundaar the power of the Source, the Doctor will die…

Part Three. After returning to Traken, the Doctor tells Nyssa they will leave after he has attended the Consular enquiry regarding Kwundaar. He informs the Consuls of what he learnt and speculates about Kwundaar's origin. Following their departure in the TARDIS, the Doctor is determined to know what Kwundaar wanted in the Source Interface vault and takes the TARDIS back. Consul Janneus wonders why Kwundaar simply waits beyond the Union. The Doctor and Nyssa enter the vault via the healing spring where the Doctor realises the chamber predates the Source itself, like the temple-like building housing it. When the enemy fleet amasses, the Consuls are confident there is no threat with the Source functioning. The Doctor boosts the Source's protective shield to make it harder for Kwundaar to possess. Traken comes under attack from Kwundaar's soldiers and when the sun turns black, Nyssa realises that by boosting the shielding, the Doctor has stopped the light of the source escaping, leaving Kwundaar free to take it…

Part Four. As Kwundaar orders the Source vaults opened, he realises the Doctor and Nyssa are nearby, plotting against him. The Doctor believes Kwundaar does not have complete control of the Source but Kwundaar's forces capture him and Sabian, while Nyssa evades Anona thanks to the infused energy from the Source in the water. The Doctor realises Kwundaar is connecting the Source Manipulator. Nyssa confronts Kwundaar, but, overwhelmed, she is forced to configure the Source for manual control. Kwundaar was the God of Traken, but was driven out by the Source - the ultimate expression of science. Narthex shoots Anona to save the Doctor, knowing he is the only one who can stop Kwundaar. The Doctor enters the Source, leaving Nyssa with instructions to lock it down when he has control. Kwundaar and the Doctor battle each other's wills, but the Doctor tricks Kwundaar into giving him control. When the shielding is lowered, the power of the Source destroys Kwundaar and the Doctor asks Shayla to become the first Keeper of Traken, so she might restore the Union.

Jacqueline Rayner (Executive Producer for BBC Worldwide), Clayton Hickman (Front Cover), Russell Stone (Music Composition), Jason Haigh-Ellery (Producer), Gary Russell (Producer), Alistair Lock (Recording & CD Mastering), Gareth Jenkins (Sound Design & Post Production)

Nyssa will die at dawn, and the Doctor doesn't even know why.

To save her life, he must make a desperate journey to the only place in the universe where a cure might exist.

When even that fails, the Doctor has a choice -- let Nyssa die, or make a deal with the devil.

After all, the road to hell is paved with good intentions...

A prequel to "The Keeper of Traken," this story features the secret of the Source and the identity of the first (and second) Keeper of Traken. Stephen Greif is known to fans as Travis in "Blake's 7"; Susan Penhaligon appeared in the Doctor Who serial "The Time Monster".

"Radio Times"-style Interior Blurbs: Part One - Nyssa has twenty four hours to live, and there's only one place in the universe the Doctor can go to for help.
        Part Two - Will the Doctor really make a deal with the devil to save Nyssa's lif? And if so, what can the Doctor possibly offer him?
        Part Three - Has the Doctor escaped, or is he walking into a trap? Will Nyssa live to see the next dawn?
        Part Four - The Doctor has handed the ultimate power in the galaxy to a dark god. All is lost.

Extended Synopsis: An episode-by-episode detailed breakdown can be found at Dominique Boies' Dr. Who Reference Guide.

The DiscContinuity Guide:: Lots of information about this story, including continuity,technology, dialogue (pro and con) and story elements, can be found by clicking here.

Big Finish Productions: Click here for the official Big Finish website.