BEST FRIENDS FOR LIFE: Two orphaned cousins, Elizabeth (Sarah Gadon, left) and Dido Belle (Gugu Mbatha-Raw) were taken in by their wealthy aunt and uncle to be raised on their estate in England. The cousins, who were close in age and were adopted when they were eight-years-old, soon became fast friends for life. As they were growing up, Belle’s African lineage brought her into contact with racism and slavery issues that were being debated in England at the time.

Born in the West Indies in 1761, Dido Belle (Gugu Mbatha-Raw) was the daughter of Mary Belle, an African slave, and John Lindsay (Matthew Goode), a British ship captain. After Mary died, the widower brought his 8-year-old daughter to England to see whether his wealthy aunt and uncle would be willing to raise her.

Lady (Emily Watson) and Lord Mansfield (Tom Wilkinson) had just adopted another niece whose mother had passed away. Also, because Dido and Elizabeth (Sarah Gadon) were about the same age, the orphaned girls could keep each other company.

Captain Lindsay claimed that his daughter was entitled to live on the family estate because of her noble birthright. This prompted a skeptical Lady Mansfield to speculate about whether skin color ranked above or below a person’s bloodline in English society.

Ultimately, she agreed to raise Dido, and the two young cousins forged a close friendship that lasted for life. Proof of their close bond has been preserved for posterity in a striking portrait of the pair that was commissioned in 1779.

That famous painting apparently served as the inspiration for Belle, a mesmerizing biopic based on a script by Misan Sagay. Directed by Amma Assante, the riveting historical drama is another movie in the recent series of pictures — such as Django Unchained, The Retrieval, and Oscar-winner 12 Years a Slave — that reexamine race from the black perspective.

The film focuses primarily on Dido and Elizabeth’s coming-of-age against the backdrop of a country that is becoming increasingly uneasy about its involvement in the slave trade. After being protected during their childhood, racism becomes an issue when the young women become involved with suitors whom they meet outside the safe confines of the family estate.

Meanwhile, tension also builds around a legal decision that was about to be made by their uncle Judge Mansfield, who was the Chief Justice of England’s Supreme Court. The case was about a trading company that was seeking compensation from its insurance company for the loss of over a hundred Africans who had been deliberately drowned.

The question Judge Mansfield was being asked to resolve was whether or not slaves should be considered to be human beings or merely cargo that could be thrown overboard for financial gain at the whim of the owner. The longer he agonized over the ruling, the more he felt pressured to issue a landmark opinion that was likely to be the death knell of an odious institution.

Excellent (****). Rated PG for smoking, mature themes, and ethnic insensitivity. Running time: 104 minutes. Distributor: Fox Searchlight Pictures.

—Kam Williams