Holly tracks an apparently part mechanical, part biological vessel and Red Dwarf latches onto it with its suction docking clamps. The Dwarfers then enter and begin to explore the interior of the alien-looking vessel. Inside, Kryten and Rimmer find a malformed, triple-headed skeleton which falls through Rimmer and causes him to loose his bowels and call for his mother. Using the Psi-Scan, Kryten deduces that the corpse is a augmented human, and that the vessel, although very advanced, is from Earth.
Meanwhile Lister and Cat find a chamber with highly advanced machinery. Cat beings to tamper with it, which causes Lister to be trapped in a forcefield. Cat continues to tap away at the controls, despite Lister telling him not to and to go get Kryten. Lister is then accidentally transmogrified into a chicken, then a hamster, before Kryten and Rimmer enter.
Cat goes over what he did and begins the same process, this on Kryten, who is trapped in the forcefield. Kryten is calm at first, since he is synthetic and therefore immune to the machine, but then he engages his panic circuits as he realises that his brain is part organic and therefore the too can be altered. Cat presses some random keys and Lister is changed back to a human. When pressing what he did for Lister to free Kryten, the machine transforms Kryten from a mechanoid into a human.
This has resulted in Kryten's dream of becoming human coming true, physically he has the body of a thirty-year-old human male, but everything is new to him. Lister greets him and serves Kryten's first breakfast of "boiled chicken ovulations". Kryten goes over a list of things he has discovered about himself now he's human. He discovered that human eyes don't have a zoom function, his nipples don't pick up short wave radio transmissions and that he needs to eat and sleep to recharge, not stick a lead in the "socket". Lister tells him that humans don't have such features. Next Kryten wants to talk about his penis, which Lister sniggers at first. Kryten has taken Polaroid photographs of his penis which he shows to Lister not believing that is how it's meant to look. After finding out that super deluxe vacuum cleaners give Kryten a "double Polaroid", Lister tells Kryten he should change back since he was never meant to be human, but Kryten doesn't want to.
Rimmer thinks the machine is the greatest advancement mankind has ever made and wants to use it to create a new body, cloning it from his old dandruff, but Cat sneezes it away. Cat doesn't want to use it as he doesn't see anything that he wants to improve, Lister believes that Kryten is in for a major disappointment, talking about the time when Kochanski dumped him and how he wished he were a squirrel because he saw one that was happy with its life.
Kryten goes to visit his Spare Heads. He describes how wonderful it is being human and not a second class mechanoid. A heated argument gets under way, especially with Spare Head 3, which suffers from droid rot and has a Yorkshire accent. Spare Head 3 tells him to "sling yer bloody hook" and a Spare Hand gives Kryten a two fingered salute. This makes Kryten depressed, Lister convinces him to change back by telling of his own shameful instance in which he went against who he really was by going into a wine bar. The moral of the story is that you are who you are, a quote they can't agree who said it, either Sartre or Popeye the Sailor Man.
When at the DNA suite, Holly gets ready to change Kryten back, but Rimmer wants to test it first using the tin foil container holding Lister's unfinished curry, which results in the creation of the Mutton Vindaloo Beast, a giant ravenous beast that wants them dead and is invulnerable to bazookoid fire, as it is made from vindaloo mutton.
They retreat back to the DNA suite and Lister asks Holly to turn him into "Man Plus". Holly activates the sequence but turns Lister into a miniature version of RoboCop. When the others run away from the beast, miniature cyborg Lister is cornered and then realises that the beast is burned like acid when it touches Leopard Lager, beer being the only thing that can kill a vindaloo. Lister throws a can of lager into its mouth, and shoots at it with the bazookoid, blowing its head off. When the others return, they are disgusted to find Lister is eating some of the Mutton Vindaloo Beast saying "Has anyone got a poppadom the size of Lake Michigan? This stuff's really good."
Available on the Series IV DVD:
- At least six cut dialogue scenes and jokes.
- A scene was filmed with the three-headed mutant corpse falling through Rimmer; in the broadcasted edit, this event went unseen but was recounted to Lister by Kryten.
- More of the Mutton Vindaloo Beast is seen. As it comes at the Robo-Lister, he fires off a number of blasts from the bazookoid which miss the Leopard Lager can in the beast's maw, before finally hitting it and blowing up the beast, therefore more closely mimicking the ending of Jaws.
- Lister notes that the events of this episode take place exactly "one year to the day" from the events in the episode "Polymorph", on Easter.
- This episode marks the first appearance of Kryten's Spare Heads, and notably Spare Head 3.
- Lister mentions Kryten, after he insulted his spare heads, having his "head up his recharge socket", which hints at where it is located.
- The hologram Rimmer finds a three-million-year-old piece of his dandruff, the only thing left of his former human self. Rimmer intends to use the DNA Ship to recreate his physical body from the genetic structure within the dandruff; however Cat scuppers this plan by sneezing the speck away. This concept is reused from the "lost episode" of Series I, "Bodysnatcher", where a similar event occurs.
- The D.N.A. Machine recognizes Lister's accent as a "colloquial English Dialect, 23rd Century". This is strange given that other episodes have said Lister comes another century, such as the 21st century, for example in "Stasis Leak", and also from the 22nd century, such as in "Ouroboros". This inconsistency has never fully been resolved, although multiple time-lines have been created and ended throughout the run of the show ("Timeslides", "White Hole", "The Inquisitor", "Out of Time", "Pete"), which may go some way to explaining it.
- On the DNA ship, the boys find a mutated astro with three heads. In the Series VIII episode "Krytie TV", they encounter a similar mutant.
- The armour Lister wears when he's a "superhuman" resembles that of RoboCop.
- In this episode, Lister wears a t-shirt advertising "Believe in the Ruins". This is possibly a reference to a 1984 vinyl of the same name by Californian "Oi!" punk band Killroy. This would certainly fit in with Lister's counter-culture aesthetic.
- Lister also wears the same t-shirt at one point in Series X.
- Rene Descartes is not known to have said "I am what I am"; in fact, his most famous quote, the Cartesian Principle, is "I think, therefore I am". Therefore, in a rare subversion, Rimmer's supposedly erroneous assertion that it was 'Popeye the Sailor Man' that said it, rather than Descartes, is surprisingly accurate.
- The name of the episode "D.N.A." is described in the commentary on the DVD as standing for 'Do Not Alter'. The acronym D.N.A. also stands for Deoxyribonucleic Acid, the basic building blocks of life.
- Robert Llewellyn admitted in the DVD commentary for the episode that he wasn't familiar with the full version name for Deoxyribonucleic Acid at the time, and came to believe that 'Do Not Alter' was the long form of the acronym for a while.
- This episode has several subtle references to Hitchhikers Guide to the Galaxy. D.N.A. are the initials of Douglas Noel Adams. It is episode 2 of series 4, which could be written as episode 4.2 - leave out the dot and you get 42. The skeleton with additional heads could be be a reference to Zaphod Beeblebrox.
- Lister's reaction to Kryten's "double Polaroid" was not actually planned: Craig Charles had no idea he'd be seeing the real thing, and was quite startled when he realized what it was.
- This is one of two episodes in Series IV that allowed Robert Llewellyn to perform scenes outside of his cumbersome Kryten makeup, the other being "Dimension Jump".
- Lister's relationship with Kochanski is retconned in this episode; while he was established to have merely pined after her before, it is now stated that just like in the novel the two did enjoy a brief relationship.
- Kryten: ...Oh. Wait a minute. No. My brain is part-organic, and therefore it is entirely possible for the machine to transmogrify my physical condition. Engaging panic circuits. Panic circuits engaged. Mwah-heh! (Cries)
- Human Kryten: (Hands Lister a photo. After realising what it is of, Lister turns away) Well?
Lister: We-we-well what?
Human Kryten: Well, what do you think?
Lister: I'm not quite with you here, Kryten. What am I supposed to say?
Human Kryten: Well, I want to know is that normal?
Lister: What? Taking photographs of it and showing it to your mates? No, it's not!
- Cat: Last time, it was hors d'oeurves... this time, it's lunch!
- Kryten: You sold out? Hmm.
Lister: Look, this is between me and you, OK, Kryten? Once, many years ago I went into a wine bar.
Kryten: That's it? You went into a wine bar? - OK.
Lister: Keep it down! - I don't want the whole world to know.
Kryten: What's so bad about going into a - a "WB"?
Lister: It means I was a class traitor. I could have been on that slippery slope - hankering after pine kitchens, sleeping on futons, eating tapas. Who knows? I could have started having "relationships" instead of "going out", got married, got on the property ladder. Who knows where it could have ended? Next thing you know, I'm playing squash every Tuesday night with a bloke called Gerald. A lucky escape, man.
Kryten: I want to be a mechanoid again.
Actor and character they played.
- Richard Ridings as the D.N.A. ship computer
- Paul McGuinness as the Curry Monster