"Knock Knock" begins with a premise as old as cinema itself: a man alone in his house, two mysterious women at his door, and the rain coming down in sheets. But Eli Roth, known for his gleefully grotesque "Hostel," has something more unsettling in mind than mere bloodletting.

Keanu Reeves plays Evan Webber, an architect whose picture-perfect life includes the requisite beautiful wife, adorable children, and modernist house that practically screams "successful professional." When his family departs for a beach weekend, leaving him behind with a shoulder injury, two young women (Lorenza Izzo and Ana de Armas) appear on his doorstep like wolves in sheep's clothing.

What follows is less the expected splatterfest and more a psychological descent into modern anxieties about fidelity, social media, and sexual power dynamics. Roth, typically a conductor of grand guignol orchestra, here plays a subtler tune. The violence, when it comes, is more emotional than physical, though no less devastating.

The film's most interesting choice is its reversal of home-invasion thriller conventions. Instead of brutish men terrorizing a helpless family, we get two seemingly innocent young women whose childlike affect makes their eventual revealed nature all the more disturbing. They're less interested in Evan's blood than his complete psychological destruction.

Some may find the film's more outlandish moments jarring, and Roth occasionally lets his camp sensibilities get the better of him. But there's something compelling about watching this man's carefully constructed life dismantled by forces that seem to have sprung directly from our collective digital-age nightmares.

"Knock Knock" isn't Roth's best work, but it shows him maturing as a filmmaker, trading gore for psychological gamesmanship. It's a thriller that understands sometimes the deepest cuts leave no visible scars.

Three stars.