Michael Morpurgo’s children’s story is a boy’s-own desert island adventure, closer in spirit to The Coral Island than Lord of the Flies, and here attractively presented as a family animated feature, adapted by the children’s laureate Frank Cottrell-Boyce. The story itself makes clear that the action must be happening around the time of the original novel’s publication in 1999, and not really the present day.

Michael (voiced by Aaron MacGregor) is a moody, lonely boy on a round-the-world sailing trip with his family, but his immaturity and unreliability exasperate his older teen sister (Raffey Cassidy) and parents (Sally Hawkins and Cillian Murphy). Unbeknown to any of them, Michael has smuggled his beloved dog Stella onboard and when their craft hits stormy seas, Michael and Stella get washed up on a remote island which he soon discovers is in fact the private kingdom of an elderly Japanese second world war veteran, Kensuke (Ken Watanabe) whose own story is a poignant and awe-inspiring contrast to Michael’s.

In some ways, Kensuke’s existence cancels the jeopardy of Michael and Stella’s arrival on the island and solves the terrifying question of how they are to get food and water; Kensuke obligingly (if mysteriously, at first) provides these. But then Michael is to find that the island is home to apes and other animals which are being hunted by sinister people who show up in a boat, and for a while these apes, and not Michael, assume a virtually centre-stage position in the story.

Another type of story might have pondered the possibility that Michael would simply get older and inherit Kensuke’s position as “king” of the island and die there himself in due course, alone. Well, a happier and simpler ending is at hand. It’s rather Spielbergian in its way (Spielberg filmed Morpurgo’s War Horse) but more low-cal.

• Kensuke’s Kingdom is in UK and Irish cinemas from 2 August.