Adam Wingard's The Guest opens with a wet-eyed woman (Sheila Kelley) sitting so still in a chair in her desert ranch house that all we hear is the clock loudly counting seconds. We sense that she's been sitting like this for months, and the film is charged with anticipation. Horror, like this grieving mother, is waiting for a change. And horror has never had a movie quite like this.

The doorbell rings, and this confident, swoony and hilarious thriller gets going. On the porch is just-discharged veteran David (Dan Stevens), who served with Laura's dead son, Caleb, and swore he'd stop by to tell the family how much their boy loved them. David has a soft voice and ends every sentence with “ma'am” or “sir.” His photo is right up there on the mantel: a shot of Caleb's brigade. He doesn't want to intrude; he's merely passing through on his way to Florida to look for work. And so Laura begs him to stay and sleep in Caleb's old room, at least for a few nights.

“What if he has the PTSD or whatever it's called?” cautions her husband (Leland Orser). Their high-school-age son, Luke (Brendan Meyer), is also on edge, as is their 20-year-old goth-babe daughter, Anna (Maika Monroe), who's worried about her parents' fragile stability. The Peterson family's fears aren't off-base. There's something wrong under David's surface that we sense before any of them admit it, something in the way the light in his neon-blue eyes shuts off whenever he's alone.

But boy, is that surface seductive. David soon wins over everyone. He's the real Captain America: polite, protective, charming and a walking cloud of pheromones. Wingard delights in shooting him like a sexy car. In one scene, David startles Anna by exiting a humid bathroom wearing nothing but a towel and a wisp of steam. Later, he enters a party carrying a keg in each hand, and the drunks freeze in their place, the girls stricken with lust and the guys with shame.

The film around him is just as glamorous — it looks great and sounds even better, thanks to a sensual electronic soundtrack that Wingard includes in scenes as the mixtape that Anna presents to David after a night where she's almost tempted to join this stranger in the bedroom down the hall.

Reduced to a two-sentence pitch, The Guest sounds like a ripped-from-the-headlines horror flick about traumatized veterans, but it's not designed to outrage or offend. It wants to have fun, so it makes David both the immediate threat and a victim, himself, of a mysterious government program headed by The Wire's Lance Reddick, which it never bothers to explain. (“Experimental military program” is enough to make audiences hiss.) It even lets us believe that this killer with Terminator grace might actually love this family, even as he resolves to murder it.

This is a star-making role for Stevens, best known as the blond heir Matthew Crawley in Downton Abbey. Stripped of his tweeds and given a polo shirt and mild Southern accent, he looks modern and manly. He moves with real menace, grins as if he always gets the girl and proves he has a range that expands far beyond the British countryside. More importantly, Stevens plays David unironically. He's funny but never campy, and manages to nail the deadpan humor of a scene where David mentors Luke to intimidate bullies by burning down their houses with their families inside. (And Meyer knows to respond with quiet, please-say-he's-kidding alarm.)

Wingard and screenwriter Simon West's last comic chiller, You're Next, got chuckles from being a smart spoof on slasher flicks. It was knowing and clever, but The Guest is straighter and better, its own organic delight. Most films that try for laughs and screams make themselves the joke, as though saying, “Isn't it hilarious that we're slumming it with scares?” But their characters are too silly, their beats too ironic and telegraphed; as a result, their deaths don't pack a wallop. There's nothing more wasteful than empty slaughter, even if we giggle at the gore. The Guest transcends the genre with characters who could have come out of a more serious movie. We laugh with them, not at them. When they're in peril, we actually care, and Wingard respectfully makes the kills clean and quick.

The Guest delivers on everything — the sex, the humor, the menace, the cool — and even though it climaxes in a haunted-house maze chase we think we've seen before, we've never seen it this good, this playful or this ambitious. As the fog from the smoke machine swirls around David and the fleeing Anna, the moment is almost romantic. We sense that she's twice as upset because she nearly fell under his spell. It's OK, dear — we have, too.

THE GUEST | Directed by Adam Wingard | Written by Simon Barrett | ArtAffects Entertainment | ArcLight Hollywood, AMC Century 15

Advertising disclosure: We may receive compensation for some of the links in our stories. Thank you for supporting LA Weekly and our advertisers.