When you watch writer-director Francois Ozon’s In the House, you’re obviously watching a film. But you’re also arguably watching a film-within-a-film, and hearing its script read as it’s acted out. The story, which Ozon (Potiche, Swimming Pool) adapted from a play, centers on Germain (Fabrice Luchini), a high school literature teacher who regards his students as “barbarians” who can’t write. But as he’s grading papers one day, Germain reads the essay of a teenager named Claude (Ernst Umhauer), who captivates his instructor with a well-written piece about a classmate and his house: For a long time, Claude used to sit in the park across from the house, admiring it and its “holy family.” He wants to see what life is like inside, so he befriends the classmate, Rapha (Bastien Ughetto), by offering to tutor him in math.

Claude describes the interior and Rapha’s mother (Emmanuelle Seigner) in somewhat disparaging terms, highlighting their stereotypical middle-classness. “To be continued,” Claude writes at the end. Germain is intrigued, as is his gallery-curator wife, Jeanne (Kristin Scott Thomas), and he decides to mentor Claude and urge him to keep writing about the insincere friendship, though it’s not clear whether Germain is doing so to satisfy the teacher or voyeur in him.

Also unclear is Claude’s motivation, which is the sole fault of the otherwise intriguing film. Near the end of it, Claude tells Germain, “There’s a way into every house.” But we don’t learn if this is the first time he’s done it, or if there’s something lacking in his life to prompt his actions. As they continue their project, Germain offers guidance to develop this character or rewrite another, and there comes a point when you don’t know if what Claude is writing is fact or fiction. In later scenes, Germain will surrealistically pop up to give instruction like a director would. Whether or not Claude actually experienced what he writes, how Germain regards the essays is bluntly stated: When Rapha’s parents show up to one of Jeanne’s exhibit openings and she wonders if they should talk to them, Germain says, “They’re fictional characters, Jeanne.”

In the House is being promoted as a mystery/thriller, though the only true mysteries are the holes in the script. Umhauer’s Claude does have a creepiness about him—he’s a little too smooth and manipulative for a teen—and his obsession crosses into stalker territory. But we have no way of knowing whether he’d keep being a part of Rapha’s life on his own, or if he only does so because of Germain’s encouragement. A mystery should keep you guessing, but not quite like this.