I will give Focus Features this: the trailer for The Book of Henry is not misleading. When I first saw it, I couldn’t believe that was the movie. How was a movie about a precocious, 11-year-old who’s helping to raise his little brother and his immature mom also a film about the mom trying to assassinate their next-door neighbor because he’s molesting his stepdaughter? Those are two completely different movies. It’s like blending Capri Sun with absinthe. And yet that’s pretty much the movie director Colin Trevorrow made. He plays Gregg Hurwitz’ script completely straight, and what could have been a story about a child unable to come to terms with evil in the world instead becomes a dehumanizing mess that rides its high concept straight to hell.

Henry (Jaeden Lieberher) is a boy genius looking after his irresponsible mother Susan (Naomi Watts) and little brother Peter (Jacob Tremblay). While Susan spends her evenings playing Gears of War and getting drunk with her co-worker Sheila (Sarah Silverman), Henry is taking care of the finances, playing the stock market, and building Rube Goldberg machines. He’s also trying to help his neighbor Christina (Maddie Ziegler), who’s being sexually abused by her stepfather, the police commissioner Glenn Sickleman (Dean Norris). Henry tries to play by the rules and report the crime, but no one will confront the powerful commissioner of a small, peaceful town, so he takes it upon himself to rid the world of Glenn. However, due to unforeseen circumstances, he must hand the task of murdering Glenn off to Susan.

The Book of Henry feels like it started out as a much smaller, more personal story that went horribly off the rails in an attempt to make it more compelling. A story about a single mom with a smart son and a normal son isn’t “big” enough on its own, so it sets up the whole plot about “Well, what if the smart son realized the girl he had a crush on was being raped by her stepfather and set up an elaborate plan to kill the stepfather?” At that point, you’ve pretty much not only left reality, you’ve also left the whole “The son is really smart” part because Henry has come to the same conclusion any dummy would have: vigilantism. Henry is supposedly brilliant, but his solution to Christina’s situation is that if the system doesn’t work, you have to take matters into your own hands.

That conclusion makes Susan out to be an even worse mom than the movie presents her to be. On its own terms, The Book of Henry would like us to view Susan as irresponsible and immature, but her heart is in the right place. She loves both her sons, shows them lots of affection, and chooses to go to work even though Henry has already made her rich on the stock market. However, when it comes to teaching her sons right from wrong, Susan seems to be at a loss. It’s a tough lesson that there’s evil in the world we can’t do anything about, but the movie is so hellbent on patronizing Susan at every turn that when Henry remarks that apathy is worse than violence, she has no answer for him.

In order to dig into the film’s larger problems, I’m going to have to dig into spoilers, so if you’re determined to see The Book of Henry, stop reading now.