There’s a shatteringly tense moment early in The Trigger Effect that cuts so close to the bone of contemporary life it raises hopes that the film ultimately fails to fulfill.

Matt (Kyle MacLachlan), a dignified yuppie, asks two obnoxious loudmouths to settle down in the middle of a movie. One of the chatterers unleashes a stream of profane invective against Matt and his wife. Annie (Elisabeth Shue), looks at Matt to stand up to the jerks: What will he do? Does he have the guts to avenge the public insult, or, given the possibility that these strangers have a gun, will he back down in humiliation?

It’s the kind of situation most of us find ourselves in at some time or another. Matt, defeated, leads his wife away to another part of the theater. You feel his humiliation and powerlessness, because you have been there, too.

It’s a terrific set-up for The Trigger Effect, the directorial debut of screenwriter David Koepp. Koepp, who also wrote the script, explores the savagery underneath the veneer of civilization, which Koepp suggests is stretched thinner and tighter than we think. When a mysterious blackout plunges Los Angeles into several days of darkness, the comfortable assumptions that allow Matt and Annie to live in a stable peace, evaporate.

During the blackout, a construction worker friend, Joe (Dermot Mulroney), drops by to wait out the crisis. Matt’s capable of providing for his family when the lights are on, but the more primitive conditions make him look weak. The blackout exposes stress fractures in Matt and Annie’s relationship, and the tougher, less refined and intelligent Joe – who’s not as successful as Matt when the electricity hums, and resents him for it – suddenly looks to Annie like a more attractive alternative.

The Trigger Effect is most effective in exploring within the bounds of a suburban neighborhood the meaning of manhood in contemporary society. The sexual tension among this trio is dangerously volatile; watching the first half of this movie is like being in a room slowly but steadily filling with natural gas (and testosterone). But Trigger dissolves when the group, for illogical reasons, abandons the house for a roadtrip to Colorado. The denouement, which tries to be a broader indictment of selfish individualism, proves forced and unsatisfying.