[On the command deck of the human space-base thingy. Replay the cliff-hanger from last time, carefully edited to save space.]
TAMPAX: Since the late twentieth century, we have been toying with your puny space projects. Remember SkyLab in 1979? That was us. The Space Shuttle in 1986? That was us too. The Optus satellite that got lost in 1993? It is safe, in the spare room back on Mothball 6!
COMMANDER FLEGGLE: Yes, yes, I see... you've made your point!
PENTAX: I'm glad to hear that, Commander. Because we've just realised that it's almost time for the cliff-hanger. And you're going TO DIE!
COMMANDER FLEGGLE: (Gasp!) But...
PENTAX: Don't worry, that was just for the cliff-hanger. Now, where were we?
COMMANDER FLEGGLE: Oh thank goodness. Does anyone know where the toilet is in this place? C'mon, in the space of four episodes, we get to see the inside of this base thoroughly, but there's never any toilet!
PENTAX: For you, Commander, the fate is much worse. After you have the Doctor's help in defeating us with some sort of gas or chemical lethal to our race, you will never be seen in a quality drama again, and will be relegated to panto for the rest of your career!
COMMANDER FLEGGLE: Oh no I won't!
PENTAX: Well, that speaks for itself, really.
JANYETTE: Doctor, what are we going to do?
DOCTOR: Hmm? Sorry, I was just looking at what revolting taste my last incarnation had in clothing. How can you take anyone with question marks on his collar seriously? Oh well, another dime, another Doctor. Well now! We could call in the Timelords, who would defeat the Unrealistatrons by scaring them off with their robes; or we could use the self destruct mechanism to blow up the entire base, with the significant disadvantage that we'd be killed and we're hoping to film another story next week... or...
COMMANDER FLEGGLE: Yes Doctor?
DOCTOR: ...or we could sneak off to a handily positioned chemical storage chamber and release gases or chemicals that are harmless to humanoids but lethal to humanoids dressed up in big green costumes as Unrealistatrons. Just as Pentax suggested.
COMMANDER FLEGGLE: Sounds good to me.
DOCTOR: Well, it should work, it's worked before, in "Warriors of the Deep", "The Krotons", "Robot", "Resurrection of the Daleks"...
[The Doctor, Janyette and Commander Fleggle sneak off, unseen by the Unrealistatron guards. Pentax and Tampax are busy playing a game of Pong on the Base Defence Computer.]
The Commander puts his hand on a plastic plate which lights up, and the door opens. Just then an Unrealistatron guard comes lumbering down the corridor, sees them, and lifts his gun, firing remarkably inaccurately, as the Doctor and Janyette rush into the storage room behind the Commander, who closes and locks the door, again with his hand.]
COMMANDER FLEGGLE: That was close. Now what?
DOCTOR: Well, while you two get the cylinders and start releasing the T3rd gas, I'll climb through a handily placed ventilator that leads back to the control deck and confront Pentax for dramatic effect, just as the gas starts to come in and destroy the Unrealistatrons.
[The Doctor pulls a grate from the wall and proceeds to crawl down the vent, as the Commander and Janyette open up the tanks.]
COMMANDER FLEGGLE: Good luck Doctor!
DOCTOR: You're finished!
PENTAX: Never! The Unrealistatrons are invincible! No-one can defeat us! No-one can say "Excellent" with more relish than us!
[Cue the dried ice, as chemically gassy stuff comes onto the set through a whole bunch of vents. The Unrealistatrons start to melt and fall all over the floor, and generally die etc. Commander Fleggle and Janyette re-enter the Control deck.]
DOCTOR: If only there'd been another way. Oh well, c'mon Janyette. Time to jump back inside the big obsolete blue thing and fly off to another human colony where we can be mistrusted during the first episode and generally save the day in the end...