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As Thomas Wolfe knew so well, you can’t go home again, even if you really, really want to complete an epic pub crawl while thwarting an invasion of alien robots.

Gary King (Simon Pegg) exudes a desperate, manic, reckless, self-destructive air. In his youth, his personality made him cool and popular, but as he aged without ever manging the trick of maturing into a responsible adult, he began driving people away, until even his closest friends could no longer stand to be around him.

That’s how we find him, sitting in a group therapy session, surrounded by people yet alone. On a whim, Gary decides to round up the old gang and finally complete a legendary pub crawl that they didn’t quite finish back in their school days: 5 guys, 12 pubs, 60 pints. A natural-born leader, he cajoles his old mates into traveling with him from London back to their home town, the village of Newton Haven, so as to commemorate the 20th anniversary of a night that looms large in their collective memories, most especially in Gary’s mind.

His friends have all enjoyed a measure of apparent success in their work lives — Peter (Eddie Marsan) is an automobile salesman; Steven (Paddy Considine) is a construction contractror with his own business; Oliver (Martin Freeman) is a realtor; Andy (Nick Frost) is a corporate lawyer — and, though they’ve all had their ups and downs in the relationship department, they are reluctant to return to the scene of their debauched youth. Gary, however, is blithely intent on dragging them all along, for reasons that are not immediately apparent. Clearly, he’s ignoring (or has blocked out) a large number of pages in his own backstory, and pushes past all kinds of warning signals from his old mates that his conduct has not been acceptable for a very, very long time.

Before things turn too dour, however, a new element is introduced that spins a complex tale of a major mid-life crisis into a different beast entirely. (Hint: alien robots and many fight scenes.

To be clear, even in its most bracingly dramatic moments, The World’s End keeps its priorities straight. This is a briskly-paced, dry British comedy, serving up a stready stream of witty dialogue and physical gags to go along with the dry commentary on human behavior. In it’s most humorous moments, it’s as funny as anything in the first two installments of the so-called “Cornetto Trilogy” (Shaun of the Dead, Hot Fuzz), all writen by Simon Pegg and Edgar Wright, directed by Wright, and featuring Pegg and Nick Frost in leading roles.

The trio of Pegg, Wright, and Frost were first united on-screen in the brilliant British series Spaced; then and now, their collaborations have been about friendship. Here, the bonds between Gary and Andy have been strained past the breaking point. Initially, it’s only alluded to, but it’s something that Gary chooses not to speak about, and Andy cannot forget. Since they were so tight in their youth, it’s obvious that something of great consequence separated them.

Both Pegg and Frost are playing characters who are markedly different from their personas in the earlier installments of the unofficial, otherwise unrelated trilogy; Gary is more ragged, poised over the abyss, while Andy is still and determined not to be hurt again by withholding his emotional involvement in the reunion.

As actors, Pegg and Frost are showing greater range than ever before, yet their comic timing is still right on the money, and their chemistry floods right back into the picture when called upon by changing circumstances in the story. For longtime fans of the actors, it’s a joy to behold, and even newcomers to their work will find their characterizations to be spot-on.

But The World’s End is also an ensemble piece, so Pegg and Frost are not stand-alone stars. They’re surrounded by very amiable and precisely-played performances of Considine, Freeman, and Marsan, and, adding a cherry on top, Rosamund Pike comes along for the ride as a sibling / love interest. Supplemented by Wright’s superb staging, Bill Pope’s pastoral / nightmarish photography, Paul Machliss’ in-tempo editing, Steven Price’s soaring / creepy original score, and Marcus Rowland’s imaginative production design, The World’s End is a great-looking comedy that easily expands and contracts to embrace drama, romance, and those darn robots.

This movie may represent the conclusion of the Cornetto Trlogy, but fans of smart, ambitious comedies can only hope that Pegg, Frost, and Wright will reunite again on-screen — sooner rather than later.

The World’s End opens wide across the Metroplex on Friday, August 23.