In a time of tenuous allegiances and deep culture clashes, Julian Barnes’s new novel asks, “What determines nationality? What does it mean to be included, to be excluded?” Set in Late Victorian England and based on a true story, Arthur & George alternates sections headed “Arthur” — Sir Arthur Conan Doyle, creator of the iconic Sherlock Holmes — and “George,” a Staffordshire solicitor whose tidy, provincial existence is disrupted when he’s accused of hideous crimes.

Arthur’s life begins in Dickensian dysfunction, with a weak-willed, artistic, alcoholic father who keeps his family in poverty and a strong, wise mother whose tales of Round Table knights and the family’s glorious history inspire her son. When wealthy relatives offer to send Arthur to Jesuit boarding school, “the Mam,” an “expert in all matters, from underclothing to hellfire,” advises him, “Wear flannel next to your skin . . . and never believe in eternal punishment.”

George Edjali grows up in the claustrophobic Wryley vicarage, dominated by his father’s severe Anglican beliefs. His mother’s stories are mostly about burning in Hell, but just as troubling are the random parables, like puzzles with no logic to them. Equally random is George’s abuse at the hands of “stupid farm boys and odd-talking miners’ sons.” Half-Indian, dark-skinned, myopic, he can’t see that racism drives his torment.

Arthur becomes a devotee of the British cult of Manliness; hearty, cricket-ball whacking, honor-bound to a mythical chivalry. He trains as a doctor but makes a better living as a writer. With his Sherlock Homes money, he rescues many damsels — his mother and sisters from squalor, his wife from tragic family circumstances.

George trains for the law. Conscientious, teetotaling, repressed, he finds pleasure in the punctuality of suburban commuter trains. He dreams of the day he has all of a British solicitor’s accouterments — good watch fob, respectable umbrella, partners who hail him as “Good Old George” when he picks up the lunch tab.

When the Edjalis become the object of a vicious campaign of harassment, they respond with decent English outrage. When George is accused of animal mutilation and attempted murder, he expects the justice any Englishman deserves. Instead, on scant evidence, he’s found guilty. The separate narratives meet when Arthur sweeps in with great Holmesian flourishes to clear his character.

Arthur & George is Barnes’s ode to Britain, in the time between the waning of the Empire and the trenches of the Somme. He devises a thoroughly national language that takes in Kipling’s florid prose, Gilbert & Sullivan’s lilt, Mrs. Gaskell’s delicacy, and Elgar’s pomp, merging elements of the Victorian thriller and romance to tell a whopping good tale.

But Arthur & George also examines what it means to be English. Arthur, a national hero but an admitted “unofficial Englishman,” Irish, Scottish, and a papist, has no more actual claim to Englishness than George, the son of a Parsee from Bombay and a Scottish vicar’s daughter. Despite Arthur’s improper love for another woman and his obsession with spiritualism, his white complexion and beef-eating vigor make him acceptable, included. George, with his prim fascination for the arcana of British railway law and refusal to believe that race is the source of his persecution, is excluded. And justice is denied by a “real” Englishman, Colonel Anson, who believes that despite his ostensible decency, George “yields to something barbaric, something buried deep within his dark soul.”

Arthur & George is fun, engaging, humane, and unlike any novel Julian Barnes has written.