Imbolo Mbue grew up in Cameroon, at many times without running water. The villages and towns where she lived had no public libraries. But her aunt, who had lived abroad, had a bookcase filled with Shakespeare, Dickens and Swift. While her cousins played, 10-year-old Imbolo read “The Merchant of Venice” and “Gulliver’s Travels” over and over again.

Eleven years later, as a struggling immigrant in the U.S., she borrowed a library copy of Toni Morrison’s “Song of Solomon.” She was so moved that, without any formal training, she...