“The Book Thief” is a terribly earnest and benign film, but not an especially good one. It preaches wholesome messages (tyranny bad, literacy good), but it is so dull and mawkish that it’s more effective as sedative than sermon. Director Brian Percival (of “Downton Abbey”) gives us a warm, sentimental Holocaust movie to be enjoyed by the whole family. This is a game you lose by succeeding.

The movie, based on Markus Zusak’s 2005 children’s novel, is narrated by death himself, in the soothing tones of English actor Roger Allam. He leads us on a tour through one of his busiest assignments, World War II-era Germany. For reasons never satisfactorily explained, he focuses on young Liesel Meminger (Sophie Nélisse), an illiterate orphan taken in by the childless Hubermanns, Hans (Geoffrey Rush) and Rosa (Emily Watson).

Hans is a twinkle-eyed sweetheart. An accordion-playing sign painter with a soft spot for children, he greets Liesel as “your Highness” when they are introduced. Scowling Rosa seems mostly interested in the state pension paid to foster parents, until she is revealed to (spoiler) have a heart of gold.

We follow Liesel through a rather tame round of events. There are some unkind kids at her school, mocking the girl for her inability to read. Then kindly Hans tutors her and in a trice she is devouring entire volumes lifted from the local burgermeister’s library.

A nice handsome boy (Nico Liersch) becomes her best friend. At the other end of the spectrum (not many characters here inhabit the murky middle) is a rat-faced Hitler Youth brat (Matthias Matschke) who tests her spunk. The film’s depiction of Hitler’s rise is superficial and sanitized. Disagreeable Nazis break Jewish shopkeepers’ windows, burn books in the square and march dejected-looking civilians wearing yellow Stars of David out of the town. You would think that Death would go into grim detail about what became of them, but that would sour the audience-friendly tone and curdle John Williams’ syrupy score.

Given the tough-minded tone of many young adult books turned to films, “The Book Thief’s” frolicsome tone feels dated and inappropriate. When a young Jewish man named Max (Ben Schnetzer) takes refuge in the family basement, the feeling is more hide-and-seek than life-or-death. Rush plays a good German who wants nothing to do with Nazi brutality, but the film uses cheap shorthand to indicate his emotional intelligence. Hans is a good man because he likes music and painting.

It would be nice to believe that culture humanizes its audience, but the Third Reich was probably the most art-obsessed regime of the 20th century, and all that classical music, ambitious architecture and heroic painting didn’t slow the war machine. “The Book Thief” never asks hard questions or tackles ugly truths head-on. A Holocaust film that moves viewers to yawns rather than tears has no real justification.