Henry Carpenter (Jaeden Lieberher) lives in beautiful upstate New York with his loving, videogame-playing single mom Susan (Naomi Watts), and his adoring and adorable little brother Peter (Room's Jacob Tremblay). The titular 11-year-old is a boy genius – he prefers "precocious" – who builds Rube Goldberg contraptions and who knows everything about stocks, bonds, psychoanalytic theory, and, when he is diagnosed with a fatal brain tumour, neurosurgery.

Henry’s dying wish is that his mother follow the elaborate instructions left in a red notebook, instructions that will allow her to help the withdrawn and sexually-abused teenage girl next door. The girl’s predatory stepdad, inconveniently, happens to be a police chief (Dean Norris). Her uncle, inconveniently, happens to be the head of child services.

Uncomfortable tonal swerves

Perhaps unsurprisingly, the entirely and increasingly implausible plot makes for uncomfortable tonal swerves. Themes of child sexual abuse belong in coruscating, properly upsetting films like The Silence (2010) or Michael (2011) or The Treatment (2014), and ought not to be utilised as mawkish plot points in whimsical tales of wunderkinds.

To be fair to  Colin Trevorrow, it's a brave choice of project for a director who finds himself between Jurassic World and Star Wars Episode IX. The filmmaker coaxes good performances from child stars Lieberher and Tremblay, and allows Watts's character to drink wine, bitch with her boozy best pal (Sarah Silverman), swear, and mess up, while still being a good mom.

Bum note

Against this, everything else sounds a bum note. Where to begin? The convoluted recording that allows Henry to talk to his mother long after he is dead? The appearance and reappearance of a dishy doctor? The school talent show that doubles as a murder plot?

“Sometimes a good story will remind you of who you want to be,” says Henry. Someone watching a different movie?