Grade: B-

Colin Trevorrow’s “The Book of Henry” is the sort of film that makes a reviewer’s life difficult–not because it doesn’t offer a lot to appreciate, think about, debate and criticize, but because revealing too much while discussing it would be unfair to its makers and viewers. It’s a picture that demands close attention as it winds its way through multiple plot twists, juggling highly divergent tones (some amusingly engaging, others genuinely dark) in the process. Though it’s likely to divide viewers pro and con, the fact that it attempts to do something different, defying easy categorization in the process, itself makes it worth seeing despite its flaws.

The dominant figure in Gregg Hurwitz’s script is Henry Carpenter (Jaeden Lieberher), an exceptionally gifted adolescent who lives with his single mom Susan (Naomi Watts), a waitress at the local diner run by John (Bobby Moynihan), and his younger brother Peter (Jacob Tremblay). Henry is the man of the house, overseeing an investment fund that would actually allow Susan to quit her job and buy a new car if she could tear herself away from the video games she plays obsessively, and protecting bespectacled Peter from schoolyard bullies as best he can. It’s hardly an exaggeration to say that he’s the adult in the household.

Henry also has a youthful social conscience. He tries to intervene when he sees a man threatening a woman in the market—Susan holds him back, advising prudence, but he thinks that apathy in the face of such evil is the greatest of sins. That’s why he’s so concerned about his classmate and next door neighbor Christina (Maddie Ziegler), a talented dancer whose recessive demeanor confirms his conclusion, buttressed by repeated observation of the house next door, that she is being mistreated by her stepfather Glenn Sickelman (Dean Norris). Henry tries to prod Principal Wilder (Tonya Pinkins) into reporting Sickelman to the authorities, but she demurs, noting that there’s little evidence to support the charge—and that in any event Glenn is the town’s police superintendent, with powerful friends.

Henry therefore decides to act on his own, outlining in a notebook a plan to deal with Sickleman that’s as complex as the Rube Goldberg-style contraptions he builds in his elaborate tree house. About midway into the film, however, a wrenching twist intervenes to prevent him carrying it out, and Susan will have to decide whether to take it on herself.

To say much more than that would undercut the film’s plot which, like Henry’s complicated devices, runs the gamut from the genial familial rambunctiousness of a Spielbergian fantasy like “E.T.” to grief-ridden tragedy. If Lieberher, Watts and Tremblay didn’t possess such easy rapport, it could at times have descended into mere preciousness, and if Trevorrow’s touch were less secure, it might elsewhere have become utter treacle. Even as it is, some viewers will be put off, even angered, by the picture’s extreme tonal shifts. For the most part, though, they’re managed with sufficient dexterity to be intriguing rather than irritating, though to be sure the ending requires you to swallow a high measure of coincidence as well as some actual magic.

If “The Book of Henry” is an unusual blend, however, it is a generally satisfying one, thanks not merely to Trevorrow’s obvious dedication but to the exceptional cast. Henry could easily have become a somewhat obnoxious character in the wrong hands, but Lieberher brings a soulfulness to the boy that sidesteps the problem, and Tremblay once again shows himself as one of today’s most naturally affecting child actors. Watts conveys both Susan’s undisciplined side and her maternal commitment, even if the character’s behavior in the film’s last act rather strains credulity. In her first screen role Ziegler draws a quietly compelling portrait of mistreated Christina—Trevorrow is mercifully reticent about the nature of her abuse—and only occasionally does Norris’ underlining of Sickelman’s darkness slide into caricature. Sarah Silverman, as Susan’s over-the-top co-worker, and Lee Pace, as a kindly doctor who might become Susan’s romantic interest, both register strongly, with Silverman in particular taking advantage of a couple of opportunities to shine.

Compared to “Jurassic World” and his upcoming “Star Wars” installment, “The Book of Henry” is a small project for Trevorrow, which perhaps explains why he has treated it with special care. Working on a modest budget, production designer Kalina Ivanov has fashioned a convincing small-town world (though the tree house clearly heads into the sphere of magic realism), which cinematographer John Schwartzman has captured in often striking widescreen images. Michael Giacchino’s score responds to the film’s shifting tones.

The most serious difficulty for “The Book of Henry” will be overcoming the curse of erroneous expectations. This might look like a typical summer family film, but it is far grimmer than the norm. On the one hand that makes it all the more interesting; on the other, it’s likely to surprise, and perhaps even infuriate, some parents and children. Another reason to read reviews!