It's easy to see why the 1779 portrait of Dido Elizabeth Belle and Lady Elizabeth Murray posing together inspired "Belle," a costume drama centered on the unique life of the former, the daughter of a British Navy Admiral and an enslaved African woman who was raised as a free woman by her wealthy family.

You'd be hard-pressed to find too many other works from the period that depict a woman of a mixed-race background on near equal-footing with her white counterpart.

It's easy to appreciate the stately qualities of Amma Asante's film, which depicts the splendor of an 18th-century country estate setting, features the always dependable Tom Wilkinson and Emily Watson and illustrates the travails of a hypocritical aristocracy.

But the movie is essentially stuck in neutral, so restrained and composed that it's hard to become especially invested in the events at hand. The screenplay is scattered in its combination of the story of Belle (Gugu Mbatha-Raw), who is stuck in a sort of purgatory at Kenwood House (she's too socially advanced to eat with the servants and not advanced enough to dine with her family) with the larger narrative of the Zong massacre case that helped establish a precedent for ending slavery in Britain.

Sure, Belle's uncle, the Lord Chief Justice of Britan and Wales William Murray (Wilkinson), ruled on the case as he raised her and it's fair to assume that the events were connected. It's just that there's enough here for two movies and in trying to tell both stories the picture shortchanges each one.

Belle
2.5 stars
Directed by Amma Asante
Starring Gugu Mbatha-Raw, Tom Wilkinson
Rated PG
Playing at Sunshine, Lincoln Plaza