24 November 1979
Lewis Fiander (Tryst), Geoffrey Bateman (Dymond), David Daker (Rigg) [1-3], Jennifer Lonsdale (Della) [1-2, 4], Stephen Jenn (Secker) ; Richard Barnes [1, 3], Sebastian Stride [3-4], Eden Phillips  (Crewmen); Barry Andrews (Stott) [2-4]*, Geoffrey Hinsliff (Fisk) [2-4], Peter Craze (Costa) [2-4]; Annette Peters , Lionel Sansby , Peter Roberts , Maggie Petersen [2-3] (Passengers).
|Written by||Bob Baker|
|Directed by||Alan Bromly*|
|Produced by||Graham Williams|
The TARDIS lands at the site of a hyperspatial collision between two spacecraft, the Empress and the Hecate. As a result, neither ship is dimensionally stable, risking the lives of all those aboard. The Doctor, K9 and Romana offer to help out. When a crewmember is found dead, his face lacerated by huge claws, it seems something deadly has been released by the accident.
But how is the death linked to the discovery that the killer drug Vraxoin has been smuggled aboard – and where has the supply come from?
The Doctor soon realises that the aliens stored in a projection machine may hold the answers – and that the cages holding these specimens are anything but secure as the savage Mandrels, hideous swamp-creatures from the planet Eden, tear through the corridors of the helpless spaceships…
- Working titles for this story included Nightmare of Evil.
- This story would be the final Doctor Who serial written by Bob Baker, who worked on it alone.
- * Alan Bromly is credited with directing this story, but he quit part-way through filming as a result of a vehement dispute with Tom Baker. As a result, Producer Graham Williams wound up having to complete the director’s duties uncred. The unpleasantness of this whole incident led Williams to decide that he had wished to leave the series. Bromly never directed another story for the series and in fact went into full retirement soon afterwards.
- Mandrels turn into vraxoin when electrocuted.
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