The Purge is standing proof that movie trailers really do need to get shorter. Despite the built-in intrigue of its premise, many of its most genuinely disturbing moments were given away some time ago for the sake of the promotional campaign. It makes sense; R-rated horror doesn’t often play well during the warmer months, and stops had to be pulled out. But watching the film, you can’t help but wish that you didn’t know about those fresh-faced preppies in those terrifying masks going in, if only because they offer most of the most intriguing moments in an otherwise spotty movie.

In nine years, crime in America is down dramatically, unemployment is at 1% and the “new founding fathers” have instituted a yearly, mandated event known as the Purge. During this 12-hour period, all emergency services are shut down and citizens are encouraged to find catharsis by letting the id take over. The Sandin family, however, has enough money to avoid the Purge, their home in a gated community paid for by James’ (Ethan Hawke) gift for selling protective security to other affluent families. He and his wife Mary (Lena Headey) live in luxury and buy the finest things for their young son Charlie (Max Burkholder) and rebellious daughter Zoey (Adelaide Kane).

Of course, because this is a horror thriller and something has to go wrong, the Sandins’ quiet Purge night in becomes a nightmare when Charlie has a crisis of conscience and allows a homeless veteran (Edwin Hodge) to take refuge from the aforementioned preppies, led by the hyper-polite Rhys Wakefield. When the stranger disappears into their sizable home, the Sandins realize that they’ll have to either turn him over or become the new targets. Writer-director James DeMonaco keeps the pacing tight (the film clocks in at a lean 82 minutes), and a good 95% of the film takes place in the house, giving it a primacy it might not have achieved otherwise. Unlike the meticulous buildup of similar bottle thrillers like Panic Room, wherein each scene’s spatial placement is clear, it’s hard not to get lost in the Sandin house on a frequent basis throughout.

DeMonaco also misses some major allegorical opportunities here. If anything, the details that make it into the film only make one hungrier for a more elaborate picture of its futuristic nation. The film notes early that the Purge would put the underserved at a serious disadvantage, and this lends a truly disturbing undercurrent to that 1% unemployment statistic. However, once the film locks itself into the house, what little subtlety the film manages early on goes out the window. From James’ initial willingness to surrender a homeless black man to a rabid band of rich, white twentysomethings to the ultimate revelation that even the “happiest” human beings have some violence in them, the promising subject matter is ultimately mired in thriller tropes and conveniently moronic character behavior. It’s not often that a horror movie comes along that makes you crave a sequel, but The Purge fits the bill, and that’s not a compliment. By the time the film’s message-bearing sledgehammer of a final twist rolls around, you’ll pray that another filmmaker takes the inevitable second installment and turns it into the millennial They Live that The Purge so desperately wants to be.