A young girl stranded on a South Sea island and a middle-aged writer trapped in her San Francisco apartment. What good could they possibly do each other? They each need a hero bigger than either of them, right?

Well, not on "Nim's Island," where the powerless and overlooked end up saving the day.

Based on Australian writer Wendy Orr's novel for children, "Nim's Island," is produced by the people who brought us the recent blockbuster-sized adaptations of C.S. Lewis's "Chronicles of Narnia," but who have also done a nice job pf presenting offbeat but popular young adult novels like Carl Hiaasen's "Hoot" and Louis Sachar's "Holes" into movies that preserve the original stories’ daffiness: engagingly exaggerated but somehow true to life.

Nim (Abigail Breslin, who shows that her funny, compelling turn in "Little Miss Sunshine" was no fluke) lives with her father, a scientist and young widower who, because he jealously guards his work or because he's still grieving his wife, keeps to a remote Pacific island. Nim's best friends are a seal and a pelican that seem to understand what she says. Her life with her father is paradise, until, one day, he disappears while gathering samples of plankton.

Nim, left to survive a monsoon and defend her home against modern-day pirates (really avaricious cruise directors looking for unspoiled beaches to spoil), reaches out for help to the only person as capable as her missing dad: the hero of her favorite adventure books, Alex Rover. Rover is only capable on paper, however: the "real" Alex, her hero's creator, is not only female, but an agoraphobic, germophobic, nervous wreck who hasn’t left her apartment in three months.

In the story of how these two hapless heroines find, and rescue, each other, there are life lessons you can find in any kids book: trust your better instincts, say yes to what life sends you, and you can, as the movie's poster has it, "be the hero of your own story."

But there are deeper spiritual, and even specifically Christian, teachings in "Nim's Island," if they are well-hidden. Though each of these characters ends up being braver than they thought they were, their courage is revealed when they commit to helping another character. "Nim's Island" is less about being the hero of your own story than being the hero of someone else's.

What makes "Nim's Island" interesting to Christians is who comes when help is requested. As in the story of the New Testament, where a simple, pacific carpenter shows up to fulfill the role of the Messiah, the rescuers in "Nim's Island" are not the people the characters expect. The Alex that shows up for Nim is not the Indiana Jones-like Alex Rider that swashbuckles his way out of every tight spot in her bedtime reading—indeed, when the real Alex washes up on her desert island to save her from her dilemma, it's Nim who has to drag her from the surf.

Recognizing your savior can be more than a surprise; it can come as a blow to your ego. Pity poor Nim's father, who has to swallow the fact that Nim's pelican playmate has appointed himself Dad’s rescuer, feeding him fish and bringing him the tools he needs to repair his marooned research boat.

I'm bonded by the critic's oath not to give away the ending to this endearing tale of a little girl whose paradise is threatened by pirates, storms and grief. But there is one more spiritual lesson worth noting: the best kind of savior redeems not just your immediate problems but in a way that transcends them. Whether you are a nation gone astray or a little girl with one still-grieving parent, the ultimate rescue is the offer of love.