Who will watch the watchmen? Questioned the Roman poet Juvenal two millennia ago. A question that is still as relevant today when countries all over the world are faced with the problem of how much power it is that states should have in controlling the lives of their citizens for the promise of their safety.

Though in Glenview, OH, the answer to that question should be, 'none but the very free'. The comfortable suburb of Glenview is the setting for this sci-fi thriller comedy about a group of four self-appointed vigilantes who hope to catch the murderer of one of their friends. Ben Stiller plays Evan, a Costco manager who decides it's payback after one of his workers — a newly minted American citizen to boot — has been found murdered brutally. Together with Bob (Vince Vaughn), Franklin (Jonah Hill) and strange, British-accented newcomer Jamarcus (Richard Ayoade), they plan to uncover the brutal murderer preying on the town’s citizens...only to realize that they're dealing with a possible alien infestation.

While there's definitely lots of satire to mine here as an allegory for border control and cross-cultural tensions in suburbia in the vein of Men In Black,  writers Jared Stern, Seth Rogen and Evan Goldberg avoid such controversy with immigration debates and interracial tensions becoming a sensitive topic of late in America ahead of a major election, the film instead plays like a half-hearted attempt at a satire of vigilanteism and an even less than half-hearted attempt at a parody of alien invasion films.

While the performers have good chemistry, their performances amount to little besides riffing on pre-established personas: Ben Stiller continues his tradition of wide-eyed, guileless innocence and ignorance, Vince Vaughn does his usual garrulous blowhard bit, Jonah Hill its bundle of neuroses and British newcomer Richard Ayoade as the otherwise goofball team's fount of deadpan intelligence and dry wit. It's because we never get a sense of most of these characters except as typical stereotypes of Midwestern parochiality (or in Ayoade's case, British/European mock-intellectualism), that the film never really does engage with its rather autopilot plotline.

The result is a movie that has the label of 'watch the DVD while drunk' written all over it. Diverting enough to sustain attention but too generic to grab it, this is a film of high energy but little output, no one but the very free should be watching these watchmen.