Some movies require too much work. You sit there and wonder just what was going on in the writer’s head. Or try to fathom what the director’s vision was for the movie. Or wonder what the hell people were thinking when they pictured James Franco in a lead role.

With other movies, it doesn’t take a awful lot of guesswork to imagine the creative process undertaken to get the idea from brain to page to screen or to encourage a signature from a star to a contract.

This Is The End, conforms to the latter with everything it’s got. At some point in 2007, Seth Rogen sat down with Evan Goldberg and said, “Hey wouldn’t it be a great idea to write a movie where me and all my pals play exaggerated versions of ourselves during the apocalypse?” Evan Goldberg said yes. Thus was born Seth and Jay Versus The Apocalypse, a short which has been expanded here.

And you know what? It is a great idea. Even better, it’s executed well.

The premise isn’t all that different to how it’s described above. Seth Rogen picks up Jay Baruchel at LAX and the two pals, who’ve drifted apart somewhat over the years, go to a party at James Franco’s house. Jay doesn’t think much of Seth’s new friends and it isn’t hard to see why. Michael Cera, in a hilarious cameo, is a coke-fuelled sex maniac. Jonah Hill is a pathetic, whiny, goody-two-shoes who sees the best in everyone. Danny McBride is repulsive. James Franco is James Franco.

Rogen and Baruchel leave the Hollywood debauchery to pick up a pack of cigarettes and while they’re gone, members of the public are plucked from the ground via shafts of blue light and the earth opens up. They hightail it back to Franco’s where the party is blissfully unaware of LA burning around them but it isn’t long until this external trouble gatecrashes the party with violent effect. Poor Michael Cera. Along the way, the two old buddies will realise how far apart they’ve become and have to decide if they want to do anything about it.

It’s surprising how well it works and how many of the gags hit their target. The celebs are hopelessly equipped to deal with any of this and so in lieu of any proper ideas for saving themselves, they become immersed and side-tracked in the inconsequential and the superficial. A Milky Way bar, for example, gains conch-esque significance and crops up multiple times.

The leads are all excellent. And yes, this is easily the best thing I’ve seen James Franco in in a very long time. Maybe ever. There’s very much a sense of an improvised script in places, best examples being where they slag each other off for the movies they’ve made in real life. Rogen is reminded of The Green Hornet. McBride is told that no one would ever want to see Your Highness 2. And because these are delivered in little more than under-the-breath asides, they don’t feel too contrived.

And as you’d expect from an end of the world movies, an awful of things catch fire. The special effects are used pretty sparingly as the attention is mostly focussed on the characters and this too works in the movie’s favour, prompting a more positive and impressed reaction for what are fairly basic effects these days.

With the exception of a five minute lull in proceedings just before the movie enters the final act, I really loved it. I laughed out loud so many times I lost count and just when I started to have doubts around whether they could end it well, they went and did that too. I Will Always Love You has never been put to better use.

Seth Rogen’s output is pretty hit and miss, but here not only has he made an entertaining movie, but he’s managed to build that around a single concept and still make it work as a feature rather than a short. Pretty impressive.

A triumph.