To the power of four.

Sequels! They're great, aren't they?

(By the way, this will be my geekiest/nerdiest post yet. I might have to find a couple of Julia Roberts' movies to rant about next, just to balance out the scales a bit)

But back to sequels, and how great they are. You get to see the characters you know and love face new and exiting villains in new and exciting situations.

What's that you say? Movie sequels are generally crap? A desperate attempt by the studios to wring every last nickel out of its fans without having to generate any original ideas or display any sort of creativity?

Oh, you. You're such a cynic.

When it comes to super-hero sequels, though, they tend to be improvements. Generally, the first movie in a comic-book inspired film is an origin story. The writer has to spend valuable screen time explaining exactly why an otherwise normal person would put on tights to fight the forces of evil, when any pair of slacks would do the job just as well AND have pockets to keep stuff in.

But when a sequel comes along, the makers are free to drop us straight into the action with much less setup. The villains can be bigger and badder, and our heroes' emotional attachments are something we have seen grow over the course of two movies, so there is more at stake. Also, if the first film was a success, you have a bigger budget to play with, and more street-cred with which to entice the actor/writer/craft services/director you need.

So you would think that as they go on, as the number after the title gets bigger, the movies would only get better. Today, I am going to take that thought and push it to the n^th degree. Where n = 4.

Let's look at the movies in the graph above. For completeness sake, I have counted X-men origins: Wolverine and The Phantom Menace as sequels, and speculated on the quality of the cancelled Spider-Man 4 based on the direction #3 was heading. The Alien Tetralogy is in there as well for no other reason that I like it, and it also fits the pattern.

The scores - which I have taken from imdb - vary wildly, but have certain aspects in common.

This is something I call "The rule of 4"

• Movie #1 and Movie#2 are usually as good as each other. Sometimes the sequel is almost as good as the original, sometimes it's a little bit better. The scores are generally close enough to call it a wash.
• Movie #3 varies the most in terms of quality. But in every single case above, the third film of a series scores lower than both #1 and #2.
• And as for movie #4? Forget about it. There isn't a single case where #4 is better than #3, #2 or #1. And even the best #4 scores lower than the lowest #1, and ties with the lowest #2.

I don't think this is a universal law, but it is astonishing how prevalent it is. I guess Nolan's next Batman and Iron Man 3 (or will it be Avengers 1?) will be the true test.

Batman and Robin is routinely - and justifiably, in my opinion - accused of being the worst comic-book movie ever made and Superman IV: The Quest for Peace is the "how to" in "how to kill a franchise".

But it doesn't have to be like this. Stories of superheroes don't naturally taper off into crappyness. Comic books run continuously. Superman has been published non-stop for the last 72 years, and is as good as it ever was. If the Bruce Wayne of Detective Comics #27 was real and still alive, he'd be almost a hundred (But still capable of kicking Wolverine's ass) And this longevity isn't unique to the print medium. Buffy fought vampires and demons for seven seasons without getting stale.

So why do movie franchises seem to have a half-life? And what can we do to make sure Christian Bale's Batman doesn't end up fighting Arnold Schwarzenegger high atop a frozen observatory? (Do you want me to trash your f**king freeze ray?)

I think Hollywood just needs to follow a few simple rules:

When you start to make your franchise, decide what you want to do with it in advance, and stick to it. If you have an arc you want to tell over all the movies, do so. If you have to, write a ten-hour long film and then slice it into four. Case in point: Billy Dee Williams (aka Lando Calrissian) appeared in Batman as Harvey Dent. An early draft for Batman Returns had that character in the Max Shreck (aka Christoper Walken) role, being blackmailed by Penguin and messing with Gotham's Mayoral elections. In that draft, he ended up horribly scarred by Catwoman's final kiss and would have emerged from the rubble, reborn as Two-Face, just in time for Batman Forever. An epic three-film arc just for one villain. Max Shreck and Two-Face are easily the weakest points in their respective movies; This would have solved that, in one stroke.

No bloody retcons! Darth Vader's teacher, Uncle Ben's killer, Bruce Wayne's motivations, Logan's claws and what exactly Weyland-Yutani does and does not know, once established, do not need to be trifled with and doing so will only make your fans feel betrayed.

Keep the style consistent. Somehow, Gotham went from a dark, smoky, steamy and, well, gothic city, to a neon-festooned disneyworld-on-crack adventureland in less than a decade without anyone noticing.

Do not over-use your villains. I love Lex Luthor, I really do. But there's only so many times I can see him tickle Superman with a chunk of kryptonite before I long to see Metallo burst through the wall. Or Darkseid. Or Brainiac. Or Doomsday or the Ultra-Humanite or Mxyzptlk or The Parasite or Intergang or Jax-Ur or Bizzaro or oh hell, I'd settle for Amazo the Android at this point. This goes for you too, Green Goblin.

If Joel Schumacher offers to direct your movie, turn him away with a polite but firm refusal.

Then give him seven seconds to get out before releasing the hounds.

Don't be afraid to move an aspect the story on. Clark and Lois's romance being thwarted by his double life added to the first two movies because of the "Will they/won't they" question. But when you hit the amnesia-kiss-reset-button so you can pull the same trick again, it won't work because now we all know the answer: "Yes, they could, but they shouldn't". Re-running the romance storyline after that point just seems like cruelty to Lois.

Take what works in your movie and bring it into the sequel, but don't forget to ask "Why does it work?" Batman had a cackling maniacal wise-cracking villain who stole the show. But it was The Joker, and played by Jack Nicholson. Making The Riddler, Two-Face and Mr. Freeze cackling maniacal wise-cracking villains will not replicate the success of the original.

Lastly, comic book fans aren't stupid, and our brains don't work that much differently than normal human beings. If I had to choose between Megan Fox playing catwoman or someone who could, y'know, actually act, I would take the latter any day. Story trumps spectacle. Emotion beats explosion. Acting beats looking pretty. All the rules that apply to making a good movie apply when making a good comic-book movie. Feel free to work spectacular explosions featuring pretty people into your well written and well-directed movie. Icing on a cake is awesome, but don't forget the cake.