The opening of the hugely impressive indie sci-fi yarn "Monsters" is a jangly night-vision firefight between a jeep full of gung-ho soldiers and a gigantic extraterrestrial beast. It's exciting and disorienting, plunging us headfirst into a world where new life forms have arrived, courtesy of a NASA space probe, and are staking a claim to our territory.

The high-caliber introduction also smuggles in some information that gives the story a devastating emotional impact -- if you happen to register the little details. The film, the first directorial effort by visual-effects whiz Gareth Edwards, is a stunning piece of work that packs a devastating emotional wallop. The impact is greater because it's unexpected. "Monsters" smartly plays against every expectation its title and slam-bang setup creates.

Favoring a gritty, handheld, verité style, Edwards drops us into Mexico six years hence. A huge swath of land bordering the United States is the Infected Zone, a military cordon enclosing the huge squidlike creatures. The film sustains an ominous tone that keeps us on edge; we don't see the aliens often but we sense their presence everywhere. We catch tantalizing glimpses of battle dispatches on the TV news; weathered warning signs add to the anxiety. The locals have adapted to the state of constant threat like people in any war zone. Life goes on, commerce continues -- especially the transportation business, now charging a premium for safe boat passage to the north.

Thriving on the chaos is photojournalist Kaulder (Scoot McNairy), a Latin America correspondent for an American newsmagazine. On orders from headquarters, he locates the publisher's daughter, Sam (Whitney Able) and baby-sits her until she can book a ferry home. Sam is on the run from a bad engagement; Kaulder is the absentee dad of a child he's not sure is his. As delays complicate her departure, they get to know a bit about each other and little by little we find ourselves in the midst of a suspenseful war-zone relationship drama.

The dialogue is unforced and naturalistic, the development of their unsuitable relationship is low-key and persuasive. The actors underplay their parts masterfully. By the time they begin a perilous overland passage through the Infected Zone with a posse of armed guides, we're invested in their survival. We want Sam to ditch her fiancé and reform Kaulder. But happily-ever-after is hard to achieve in the midst of an alien invasion.

"Monsters" has more in common with "Before Sunrise" or "Close Encounters" than "War of the Worlds." Edwards has won deserved acclaim for creating this seamlessly professional-looking film with consumer-grade video equipment and a four-person crew. The performances are strong, although the cast, with the exception of the leads, is nonprofessional. The dialogue is improvised, but sharply to the point. The location shooting was all done guerrilla-style, without permits. The special effects are jaw-droppingly beautiful and real-seeming. What's most impressive, however, is the way Edwards carries us along on the leads' journey from apprehension to awe to anguish. When you watch the finale, remember the opening and you'll experience one of the most audacious and poignant twists of 2010.

Colin Covert • 612-673-7186