Review: In “Heretic,” Hugh Grant is an evil, clever perfection that goes to extremes.

Hugh Grant, the British romcom heartthrob we all know from Four Weddings and a Funeral and Notting Hill, has been having a blast lately mixing comedy (Paddington 2) and villainy (The “Undoing”). Grant is evil, smart perfection in “Heretic,” which goes to extremes and is now in theaters after scoring at the Toronto Film Festival.

Starting out as his usual dapper man as the mysterious Mr. Reed, Grant oozes charm as he opens the door to his Colorado mountain home to two young Mormon missionaries, Sister Barnes (Sophie Thatcher) and Sister Paxton (Chloe East).

The young ladies are initially cautious as the rules stipulate that they are not allowed to enter any premises without a woman present. “Will my wife do that?” He winks and claims the woman is inside baking a typical American blueberry pie as he closes the door with a menacing click.

That alone should raise your suspicions. It's also hard not to notice that there's a blueberry-scented candle lying around and not a woman in sight. But Reed seems incredibly interested in talking to them about defending or losing their religion. And he resists any refusal to answer his questions.

Writers and directors Scott Beck and Bryan Woods, who broke the box office with the screenplay for “A Quiet Place,” know how to create suspense and fear. The surprise is that “Heretic” is also a mesmerizing mind-breaker that raises probing philosophical questions you don't expect to come your way.

Mr. Reed not only plays a prank on the two missionaries, who are not as naive as they seem at first glance, he also urges them to put their sermons into practice. And that requires more from filmmakers than finding new ways to terrorize us with things that happen in the night.

From the first moment, when Grant flashes an icy stare beneath Mr. Reed's casual demeanor, the young evangelists look for a way out. Her captor says he would be happy to let her go with one caveat. They must first pass his test by choosing one of two doors for the exit: On each door is written in chalk a name: “Faith” or “Unbelief.”

Which door would you choose? “Heretic” really wants the audience to take up the challenge. Reed built metal walls to block cell phone reception. Even when Elder Kennedy (Topher Grace) emerges from the church, he is quickly dealt with. We are on our own.

“Heretic” grips you like a vice as Reed struggles to convince the two missionaries – Thatcher and East, by the way, are fascinating opposites – that they are not true believers but rather stooges of the Mormon payout machine. Horror films rarely go that deep, and “Heretic” raises the bar for darkness.

Reed has built a menacing chamber of secrets in his basement, not just to unsettle us, which he does, but to raise the larger cultural question of the meaning, if any, of religion in a godless modern world.

I won't give any spoilers on the climax of the carnage and will leave the symbols of knives, poisons and cleansing fires for you to unravel. It's a weird, twisted banger, especially when Reed finds his personal religion in Radiohead's “Creep.” But this provocation is the hunt for larger game.

Grant will scare you a lot in Heretic. The dreamy romance of old has been replaced by a devilish presence that wants to send us all to hell. Open the door to this fascinating game of cat and mouse at your own risk. Mr. Reed is serious. This also applies to the film.