The Book of Henry Naomi Watts, Jaeden Lieberher, Jacob Tremblay. Directed by Colin Trevorrow. Rated PG-13. Opens Friday in select theaters.

Movies about child prodigies often go over the top with feats of pint-sized genius, but there’s never been a savant quite like the title character in The Book of Henry. Henry (Jaeden Lieberher) is only 11 years old, yet he essentially runs his family, taking care of his younger brother (Room’s Jacob Tremblay) and all financial matters while his quirky single mom, Susan (Naomi Watts), drinks with her best friend (Sarah Silverman) and plays video games. Henry also turns out to be one hell of a writer, though not in any conventional way. His so-called book is really a detailed set of instructions, meant to help Susan complete a difficult task that Henry is forced by circumstance to abandon.

Revealing much more than that would ruin this ludicrous movie’s sole pleasure, which is the sheer brazen nuttiness of its screenplay (penned by crime novelist Gregg Hurwitz). Director Colin Trevorrow is best known for Jurassic World, but The Book of Henry is more in the mold of his indie debut, Safety Not Guaranteed; both films attempt to juggle comedy, whimsy, pathos and elements of suspense, never coming even remotely close to synthesizing a coherent tone. Still, like a book that keeps you flipping pages even as you complain about the lousy prose, this bizarre stealth tearjerker at least avoids being forgettable.