Jonathan Romney on The World's End: Invasion of the lager snatchers

Pegg, Frost and Wright end their 'Cornetto' trilogy with a clever, touching comedy

Front Crawl: Frost, Pegg and Considine battle middle-age melancholia ... and killer robots

The press notes for his comedy The World's End come with a request from director Edgar Wright not to reveal the plot twists and the actors not already featured in the trailer. After checking online, I'm confident that most of what I could tell you about this follow-up to Shaun of the Dead and Hot Fuzz is already in the public domain. It stars Simon Pegg and Nick Frost, it's about a pub crawl, it features robots with bright blue lights in their eyes and, as the title suggests, apocalypse is involved. There are one or two unexpected names, one of whom is solely a vocal presence, and you'll guess who the second you hear it. Oh, and while this won't come as any surprise to Pegg-Frost-Wright fans, there's a Cornetto gag.

One surprise I didn't see coming, though, was how much fun The World's End is. It's about five men who went on an abortive pub crawl as small-town teenagers in 1990, and reunite in 2013 to finish the job. The World's End fittingly has the air of a fond, slightly nervous reunion, rather like an overdue album by a beloved band; you hope it'll be a bit different to their last, but not too different. And a lot rides on it, because Pegg and Frost without Wright (in alien road comedy Paul) didn't quite pay off, while Wright, sans the other two, gave us the exhaustingly scattershot Scott Pilgrim vs the World.

But The World's End is good – perhaps not as full-bloodedly joyous as 2007's cop spoof Hot Fuzz, but a more complete, more crafted film. It's touching too, with Pegg and Wright's script showing a sharp, rueful eye for human imperfection. Pegg plays Gary King, erstwhile teenage alpha dude in shades and a Sisters of Mercy T-shirt, now a desperate, self-deluding 40-year-old on the skids – in shades and a Sisters of Mercy T-shirt. Staring failure in the face, he's determined to revisit his home town, Newton Haven, and have another crack at the 12-pub marathon he remembers as the best night of his life – because nothing has remotely matched up since. He gets his old gang together – now successful, settled professionals reluctantly playing along. They're played by Paddy Considine, Martin Freeman, Eddie Marsan and Frost as long-time teetotaller Andy (no prizes for guessing who's first to hit the tequila shots).

Where Shaun and Fuzz were genre spoofs from the start, The World's End sets up as a bittersweet observational sitcom. For the first stretch, it focuses on the lamentable state of Gary, who can't face either adult life or the realisation that his teenage glory wasn't such a big deal in the first place. His present self only serves to clarify that the young god was pretty much a dork too – as one-time flame Sam (Rosamund Pike) is there to remind him.

In a sense, though, Gary has a point – adulthood can be a tedious business. That's where the film is so clever: it's pitched both at the hip young audience who love the genre-nudging irreverence of the trio's films, but also at viewers of Pegg's age and older who will relate to the middle-aged melancholy (and no doubt get all teary on hearing early Nineties tunes by the Soup Dragons and the Sundays). And everyone will recognise the horror of middle-England drabness that is Newton Haven, with its antiseptic pubs and streets lined with Costcutter and Superdrug.

The genre element echoes Invasion of the Body Snatchers and the John Wyndham-inspired Village of the Damned (those luminous eyes surely a nod to the 1995 John Carpenter version). The film packs a cheerful punch as a knockabout alien-invasion spoof – unusually, one structured around a series of barroom brawls – but still manages to use its science fiction premise as a metaphor for social conformity. Wright and Pegg's three "Cornetto" films are united by a coherent philosophy: a rueful nerd's-eye contemplation of the demand to grow up and put your Star Wars action figures away, but at the same time a determined resistance to capitulation and dull responsibility. They combine a love of nostalgia with unease at its stifling tendencies; this film's best set piece, capturing the infantilising horror of our obsession with retaining youth, is a pub's School Disco Night.

The film's main flaw is that, despite its concentration on character and backstory, only Pegg's Gary comes across as properly fleshed out (the other roles more or less make up the numbers, although Pike and Marsan get most chance to hold their own). But Pegg's role lets him be obnoxious, overbearing and embarrassing – almost Gervaisian, in fact – and it's a tour de force.

Overall, The World's End is breezy, sharp, to the point. And while it's had a few bob spent on it, and Wright is no slouch at dishing out a proper Spielbergian light show, The World's End still has a quintessentially British tang of cheap-and-cheerful about it. A proper draught, and no nasty additives.

Critic's Choice

Carry On Cleo! Elizabeth Taylor is regally Egyptian once again in the re-released Cleopatra (1963), as opulently excessive an epic as you'll ever see … they really don't make them like this any more. Also, Spain produces its own black-and-white silent retro oddity in Pablo Berger's fairy tale with a twist Biancanieves (Snow White to you).