How could I watch bad Star Trek episodes and not include Spock's Brain? Often called the all-time worst Star Trek episode from any series, I was slavering for this one. It didn't disappoint.

What's great about it is that it's so proud to be ludicrous. The world is full of TV that doesn't make sense in a dull, furtive way, thus lacking entertainment value. This story, though, is like the militant poster child for absurdity, marching up and down with placards. It doesn't care. It's embracing its silliness and never apologising for a millisecond. Small children and animals would snort in disbelief. I was in raptures. What's more, the comedy never gets old, but instead gets funnier and funnier.

A girl materialises on the Enterprise's bridge and steals Spock's brain. No, that's not metaphorical. She gets inside his skull and removes his grey matter. You or I might expect him to be dead, but that's because we lack 23rd century medical genius!

MCCOY - "That incredible Vulcan physique hung on until the life-support cycle took over. His body lives. The autonomic functions continue. But there is no mind."

I always thought that the brain controlled all other bodily organs and that without it our lungs wouldn't breathe and our hearts wouldn't beat, but it seems that I was wrong. Many living creatures don't have brains. Sponges, jellyfish, starfish and certain scriptwriters, for instance.

KIRK - "Bones, how long can you keep him functioning?"

MCCOY - "I can't give you any guarantee."

KIRK - "That's not good enough, doctor."

MCCOY - "If it happened to any of us, I'd say indefinitely. But Vulcan physiology limits what I can do. Spock's body is more dependent on that tremendous brain for life support.

Important fact: humans can survive indefinitely without brains.

MCCOY - "If you don't find it in twenty-four hours, you'd better forget the whole thing, Jim."

Hang on. Didn't McCoy just say he couldn't tell Kirk how long he could keep Spock's body alive? What's more, what he said isn't just a guess. It's exact. Kirk uses it as a countdown and Spock will later confirm it with "Doctor McCoy must have told you that twenty-four hours is the maximum".

Amazing. The words "Spock's brain" never stop being comedy gold. Just include "Spock's brain" in any sentence and you'll have an immediate camp classic. I love everyone for taking it so seriously, even though in reality Nimoy (to name but one) says he felt embarrassed during filming. Then it gets better! McCoy gets Spock's body walking around, with a remote control that only needs a few buttons. (No joysticks, dials, etc. Just buttons. They're not even labelled, yet Kirk manages to control Spock's brainless body well enough to make him walk towards their enemy and overpower her.)

And then it gets better still! Spock directs his own surgery and tells McCoy exactly what to do when he's re-implanting the brain. That's during the operation. They've reconnected his mouth, you see. In other words, Spock's so clever that he can perform brain surgery on himself, working blind, without even doing himself but instead just telling someone else what to do. (They don't even need to shave his head. After getting his brain back, Spock's hairstyle looks the same as ever.)

Is this (a) awesome, or (b) awesome? How can anyone bear not to watch this?

That's the funny half of the episode, but there's also a second half that's genuinely interesting and gets mistakenly called sexist. You see, the people who stole Spock's brain are idiots. They come from a super-advanced civilisation that has managed to turn its people into halfwits. They need a brain to run their control system. This is a super-duper control system that does everything for you, leaving the populace with nothing to do and no responsibility. They could degenerate into children... and they have. No one here knows anything. Thus on discovering that they needed a new brain to replace the dying old one, the people of this civilisation were no longer at a high enough intellectual level to do the job themselves.

A teaching helmet has survived, though. Put that on and you'll temporarily have all the wisdom of the ancients... but you also become cold and arrogant. Well, unless you're McCoy, in which case you can put on the helmet once (no problem) but not twice (because you'll die!!!!... don't know why).

This is intriguing. It's a pretty cool theme, if only for the unexpected reversal of making idiots of the super-advanced brain raiders who have McCoy, Scotty and Sulu creaming their jumpsuits about the implied tech levels. It gets even better when you add in the oddity of the population have split along gender lines. The men live on the planet's surface like cavemen and think of women as "the others", feared subterranean dwellers who'll kidnap you for "pain and delight". No need to ask how these people reproduce.

Admittedly this is approaching 1950s Planet of Women nonsense. It also gets worse when our heroes are patronising them, saying that they have minds like children and couldn't do anything... but despite appearances this isn't sexist, because the men were worse.

Oh, and I haven't yet mentioned the spaceship in the pre-credits sequence. Scotty's in love. "I've never seen anything like her. And ion propulsion at that. They could teach us a thing or two." Leaving aside the fact that ion propulsion existed even when the episode was written, the spaceship's design is generic, simple and dull. It was probably knocked off in fifteen minutes. It looks like a rawlplug. (This got fixed with a more distinctive design in the remastered release in 2007.)

I enjoyed the acting, by the way. Shatner is of course the king of conviction, here committing utterly to something that's beyond ludicrous, but for once he's being outdone by DeForest Kelley. I loved Shatner's fight scene with those guards, though. He's really getting into it, as he gets into everything.

In short, fantastic. I'd seriously put it in the upper half of Star Trek as a whole, although admittedly I'm an anti-fan of the franchise's incarnations from the 1980s onwards. It's entertaining, it has some genuinely cool ideas and it actually plays very well if you're watching it as magical realism. You could also have fun wondering if we're watching a society of gay cavemen. Call this story bad if you like (and many have), but I can't believe that anyone in the world is ever going to call it boring.