Polymorph

Holly detects a non-human life-form aboard ship. The crew are skeptical (the last time this happened, it was one of Lister's socks), but for once she is right. A genetic mutant – a polymorph, or shapeshifter – emerges from a mysterious space pod. This creature, the product of genetic manipulation, is an emotional vampire that can change into anything, be it animal, vegetable or mineral. It invades Red Dwarf, and it begins to feed on the emotions of the crew. First, it appears to Lister as a shami kebab and sucks out his fear, turning him into a violent maniac. It goes on to feast on Cat's vanity, transforming him into a hopeless wino. Next, it dines on Kryten's guilt, leaving him uncaring and cynical. Finally, the polymorph assumes the shape of Rimmer's mum, seduces Lister, and sucks out Rimmer's anger, leaving him a nerdy, bespectacled pacifist. The emotionally crippled Dwarfers retain enough of their senses to seek out the creature and, by luck, to destroy it in a final confrontation in the cargo hold. After they destroy it we find out that the pod contained two polymorphs...

Production notes

• This episode was the only episode to feature a warning about the episode's content immediately prior to airing. This warning is preserved in the DVD release.
• Actor Chris Barrie (Rimmer) had to wait over 10 minutes to deliver his punchline in the Kryten/Lister boxershort scene — the audience's laughter made it impossible for him to be heard.
• There appear to be two alternate endings in existence: in one, the second polymorph is seen to have assumed the likeness of Lister as it follows the other Dwarfers out of the cargo hold; in the other, it bounces down the corridor in the form of a beach ball, and an on-screen message reads as follows: EPILOGUE — The 2nd polymorph, which was much less intelligent than the 1st, stowed away in Lister's clean underpants drawer... where it died of old age many years later.
• In the scene in which the crew are searching for the polymorph, Kryten speaks in an English accent, as opposed to his usual American/Canadian accent, saying 'It's here', and 'somewhere'.
• This is an obvious parody of the first movie in the Aliens series featuring a Xenomorph.
• Error: when Rimmer, Cat and Kryten are going down the lift into the cargo bay, they are lined up from left to right: Kryten, Rimmer, and Cat. A few minutes later, without seeing them move, Cat is on the left, Kryten in the middle, and Rimmer on the end.