The apocalypse is nigh in The World's End, the concluding chapter of director Edgar Wright and actor Simon Pegg's so-called Three Flavours Cornetto Trilogy, which began with the hilarious Shaun Of The Dead then stuttered with Hot Fuzz.

Alas, the third time is a charmless exercise in male bonding, spiked with elements of The Stepford Wives as five childhood pals reunite to complete a legendary pub crawl in their sleepy hometown only to discover the locals have been replaced by robots.

The film's fictional community of Newton Haven boasts the UK's first roundabout, built circa 1909, and Wright and Pegg's haphazard script fittingly goes round in circles as the co-writers attempt in vain to bring their hotch-potch of madcap ideas to satisfying fruition.

The tone veers wildly between sci-fi, comedy, action and horror, anchored by an exuberant performance from Pegg as the most instantly unlikeable and irritating anti-hero to swagger out of British cinema in recent memory. If it's wrong to want a character dead within the first five minutes then I plead guilty now.

A prologue set in June 1990 sketches the bonds of friendship between five teenagers, who fail to complete a crawl of 12 local pubs, culminating in a final glorious pint at The World's End. Two decades later, the ringleader of that motley crew, Gary King (Pegg), decides to bring the lads back together to complete the booze-fuelled feat known as The Golden Mile.

"This time we are going to see it through to the bitter end - or the lager end!" Gary tells Andrew (Nick Frost), Steven (Paddy Considine), Oliver (Martin Freeman) and Peter (Eddie Marsan), who have all grown up, got jobs and settled down.

Everyone except Gary, who treats every crisis as a joke and couldn't care less about the emotional devastation he leaves in his wake, so long as he completes the crawl.

Tensions are inflamed when Oliver's pretty sister Sam (Rosamund Pike), who Steven has always fancied, turns up in Newton Haven. Gary's clumsy advances are politely rebuffed: "You're not a bad guy, just not boyfriend material," Sam tells him.

Romantic overtures are forgotten when Gary unmasks the strangely emotionless residents as robotic doppelgangers.

"It's not us that's changed, it's the town!" he squeals.

The World's End is peppered with cameos, none of which produce big laughs or distract from implausibilities in the plot. There's no reason why the characters would agree to follow Gary's self-destructive lead when all hell breaks loose. If anything, Andrew, Steven, Oliver and Peter would sacrifice Gary to the robot invaders to give themselves - and us - some blessed peace and quiet.

Visual gags barely to raise a smile and relationships between the characters are thinly sketched, but Pegg and Frost have their banter down pat and Pike injects a soupcon of girl power to the loopy fight sequences.