“Heretic” is a modest but effective horror thriller film about religion and faith. Now it may sound solemn and ponderous to you, the movie does a fairly commendable job of balancing itself between humor and suspense, and it will keep you guessing on what is really going on among its main characters, until it eventually reveals all as expected around the finale.

At the beginning, we are introduced to two young female Mormon missionaries: Sister Barnes (Sophie Thatcher) and Sister Paxton (Chloe East). After their casual conversation on a bench, they continue to do their job here and there in some unnamed town during one cold winter day, and then they come to a house belonging to Mr. Reed (Hugh Grant), a middle-aged guy who seems to be interested in their religion and then willingly suggests that they should come into his house for more discussion.

At first, everything feels mostly fine as Sister Barnes and Sister Paxton continue to talk more with Mr. Reed inside his house, but it does not take much time for them to sense that something is not right about him. For example, his wife is supposed to be making a blueberry pie to be served to them, but she never shows up while their conversation with Mr. Reed is being continued in the living room, and Sister Barnes later notices a certain object which makes her all the more suspicious about Mr. Reed.

As Sister Barnes and Sister Paxton become more unnerved, the movie subtly dials up the level of uneasiness on the screen. While the living room of his house looks fairly cozy, we cannot help but sense more of the growing sinister vibe under the surface, and a heavy snowstorm outside the house further emphasizes how much the main characters are isolated from the outside world. In the end, Sister Barnes and Sister Paxton have no choice but to go deeper into Mr. Reed’s house, and it goes without saying that he has a hidden plan for these two Mormon ladies.

I will not go into details for not spoiling any of your entertainment, but I can tell you instead that the movie has a morbidly suspenseful fun with toying with Sister Barnes and Sister Paxton’s supposedly strong religious faith. No, they are not your average conservative believer as shown from their conversation at the beginning of the film, but both of them seem quite devoted to their religion, and Mr. Reed is very willing to test their faith. Systemically cornering them and their faith in one way or another, he eventually pushes them into a simple but possibly risky moment of choice between two possible options, and both Sister Barnes and Sister Paxton become all the more anxious and uncertain about whether they can actually survive in the end.

The screenplay by directors/writer/co-producers Scott Beck and Bryan Woods, who previously co-wrote “A Quiet Place” (2018), is often intriguing as seriously exploring the nature of faith and religion. As Mr. Reed cynically points out at one point in the story, religion can be regarded as a mere product to be promoted and then sold while missionaries are no more than salespeople to sell it. According to him, every religion ultimately converges onto one simple thing, and he is surely ready to demonstrate his dark revelation to his two visitors once they make a choice between those two options.

When our two Mormon ladies eventually make a choice later in the film, the movie becomes less interesting than before. Nevertheless, it keeps the story and characters rolling toward to the inevitable conclusion waiting for them, and Beck and Woods and their crew members including cinematographer Chung Chung-hoon, who has been mainly known for his frequent collaborations with South Korean filmmaker Park Chan-wook, deftly maintains the level of tension to the end. As Sister Barnes and Paxton gets to know more about their host’s twisted sides, the mood naturally becomes darker step by step, and we are not so surprised when the movie briefly shows an old map associated with a certain famous classic work of Dante Alighieri.

The suspense of the film depends a lot on the talent and presence of its three main cast members, who all show considerable commitment without making any misstep throughout the movie. Hugh Grant, who has shown more of the other side of his talent during last several years since his delightful comic performance in “Florence Foster Jenkins” (2016), plays his increasingly diabolical character with sheer gusto, and he has some sly fun when he subtly conveys to us his character’s insidiousness while still looking quite well-mannered in his seemingly benign appearance. On the opposite, Sophie Thatcher and Chloe East are equally solid as complementing well Grant’s more colorful acting, and they fill their rather thankless roles with enough personality to engage us.

In conclusion, “Heretic” is a number of good elements including Grant’s surprisingly dark performance. To be frank with you, I am not that religious despite being a Buddhist on the record just like many of my family members, but I got intrigued and then entertained a lot by how the movie playfully and intensely handles the main subjects of its story, and I am really curious about how a Christian colleague of mine will respond to its thought-provoking moments. In short, this is certainly one of the more interesting genre films of last year, and I assure you that it will leave you something to think about in the end.