Years removed from his dominant run of romantic comedies, Hugh Grant, like many actors of his age, has settled nicely into “character actor” mode.

With supporting turns in movies like “The Gentlemen,” “Dungeons and Dragons: Honor Among Thieves” and “Paddington 2,” Grant takes his ability to both charm and smarm to courageous new levels.

The tense horror thriller “Heretic” transforms Grant’s familiar pleasantries into an antagonistic role that proves to be unnervingly unpredictable. Without deploying even an ounce of physicality, Grant’s Mr. Reed is able to captivate and terrorize two young missionaries using mere words (and a few carefully placed locked doors, of course).

Sophie Thatcher (“Yellowjackets”) and Chloe East (“The Fabelmans”) play two missionaries from the Church of Jesus Christ of Latter-day Saints who unwittingly arrive on the doorstep of Mr. Reed to talk about their faith. Mr. Reed claims to have a wife in the other room, but the missionaries soon learn Mr. Reed tells many lies, including one about his wife’s delicious blueberry pie.

While both women are committed to their faith, Barnes (Thatcher) appears to be more pragmatic about the world compared to idealistic Paxton (East). Mr. Reed, with a smile on his face, quickly learns the dynamic between the two of them and begins to slowly exploit it for … what purpose? The missionaries don’t quite know, but they definitely know they need to leave as soon as possible.

Mr. Reed won’t let them leave, at least not without a discussion about several distinct topics, including board games, Radiohead songs and the existence of one “true” religion. You can probably begin to see where the title of the movie comes into play.

Writer/directors Scott Beck and Bryan Woods expertly slow-play the conflict in “Heretic,” as almost half the film unspools before Barnes and Paxton come to understand the extent of Mr. Reed’s dangerous game. Thatcher and East serve as audience surrogates to Mr. Reed’s specific brand of crazy, and both actresses command the screen with quiet-yet-physical performances (because Mr. Reed likes the sound of his own voice, naturally).

The second half of “Heretic” deploys a few more traditional horror movie tropes, and while the story shift provides the film with a few more jump scares, the truly unsettling material remains with Grant’s stoic musing of sinister beliefs. Mr. Reed doesn’t seem physically threatening, but his words may kill you all the same.

“Heretic” lands in somewhat divisive fashion, though it smartly avoids commentary or criticism about any specific religion. It’s clear that Mr. Reed is an evil dude, and audiences may not be able to look at Hugh Grant’s smile ever again without feeling at least a little bit queasy.

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Tyler Wilson can be reached at twilson@cdapress.com.