Watching the children's movie "Nim's Island," you can see that it was probably a pretty good book.

The things about it that play out so poorly on the screen would work much better in print.

The two main characters change and grow, but one's story is all physical, while the other's is entirely mental. The physical part is easier to show -- at least for these filmmakers, trying to please children -- so it resonates more in the film than the mental one. The implied sense of mutual growth is lost.

The more physical character, the one children will be interested in, is Nim, an 11-year-old girl living with her father on an otherwise deserted island in the South Pacific.

Nim calls it "our own perfect secret world," and it is indeed paradise, complete with the Internet, satellite phones and a house combining the best of "Robinson Crusoe" and "The Blue Lagoon."

The island is also home to a bunch of friend animals -- a lizard, a sea lion, a pelican -- who understand English and save the day on any number of occasions. They are insufferably precious, though a few younger children may find them cute.

Parents of younger children, however, should take note that small viewers may find one scene absolutely crushing. It's brief, and only temporary, but children watching it may be devastated.

The character who grows mentally is the world-famous writer of adventure novels, Alex Rover, played by Jodie Foster.

Alex is obsessive-compulsive and a severe agoraphobic. The joke of a great creator of sweeping adventure tales who hasn't been able to leave her apartment for months is one of those aspects of the story that probably work better in the book.

Abigail Breslin plays Nim, and although her blazing talent shines through at times, she is just as often allowed to founder. Though Breslin may turn out to be the next Jodie Foster, no one could play these scenes opposite sea lions and lizards. Not even Foster when she was a girl.

Jennifer Flackett and Mark Levin directed, which may explain why the picture has such a schizo feel. The tone shifts suddenly and often, from trying-too-hard warm family fuzziness to trying-too-hard unexciting adventure to trying-too-hard unfunny comedy.

But then, like a pebble starting an avalanche -- a small avalanche -- we start to notice improvement. Foster gets off one amusing line, and then another, until she (not surprisingly) becomes quite enjoyable to watch.

Horrible tourists from a cruise ship show up to add a jolt of amusement to the story. And even those animals who understand English . . . well, they stay insufferably precious.

After such an atrophied beginning, the last third of the movie or so is actually more or less fun to watch. Viewers with little patience might just want to come in for that part.

Or better still, read a book.