The whole story is told by the horse himself. Black Beauty begins life in a quiet meadow under a kind farmer, taught by his mother Duchess to be gentle, to do his work with a will, and never to bite or kick. He is well broken in and sold to Squire Gordon at Birtwick Park, where the coachman John Manly and the stable boy James treat him and the other horses with care, and where he makes friends with the hot-tempered mare Ginger and the pony Merrylegs.
These early chapters set the book's standard of good treatment, and they also let Beauty hear other horses' histories. Ginger tells how rough breaking-in and a tight check-rein soured her temper and damaged her health, so that her bad name is really the work of careless, brutal handling rather than her own nature. Around the stable the humans voice the book's lessons directly: that there is no real religion without kindness to man and beast, and that cruelty is the devil's own trade-mark.
When illness in the family breaks up the Birtwick household, Beauty's fortunes turn. At Earlshall his new mistress demands that the carriage horses be reined up tight for fashion. The bearing-rein, forced higher hole by hole, takes the spirit out of him and ruins Ginger's wind and temper. A drunken groom then rides Beauty hard over sharp stones, and a fall leaves his knees scarred. Now blemished, he is sold down into harder, lower work.
He becomes a London cab horse, and here the book widens into a portrait of working life. Under the cabman Jerry Barker, a poor but upright man who refuses Sunday work and lives by doing as he would be done by, Beauty is decently used. But he sees all around him horses and drivers worn down by long hours and hard masters. In one of the book's bleakest moments he meets Ginger again, broken and despairing in a cheap cab, and soon after sees a dead chestnut horse carted past that he believes is her.
When Jerry falls ill and gives up the cab, Beauty sinks lower still, overworked by a cruel carter, until he collapses and is sold half-worn at a horse fair. There a kindly old farmer, Mr. Thoroughgood, and his grandson Willie buy him cheaply, give him rest and good food, and slowly restore him. By chance his new home turns out to belong to people who know his history, and his old friend Joe Green recognizes him. The book closes with Beauty safe at last, his troubles over, dreaming he is back in the orchard at Birtwick with his old friends.