Edith Wharton, the celebrated author who lived at a sprawling estate in Lenox known as the Mount, is best known as a novelist and short story writer. (If you didn’t get to read “The House of Mirth’’ or the novella “Ethan Frome’’ in high school, you got cheated.)

It turns out Wharton also wrote a play. Academics made the surprise discovery while researching the author’s correspondence with her lover, journalist Morton Fullerton, in her papers housed at the Harry Ransom Center at the University of Texas at Austin.

Called “The Shadow of a Doubt,’’ the full-length play found by Laura Rattray, from the University of Glasgow, and Mary Chinery, a professor at Georgian Court University in New Jersey, is a dark-ish satire of social privilege and affluence in England. Rattray and Chinery were also able to determine that the play was in production in 1901 — with actress Elsie de Wolfe in the leading role — but the show was never staged.

The discovery is something of a revelation since the play is nowhere mentioned Wharton’s autobiography, “A Backward Glance,’’ or in biographies by R.W.B. Lewis, Cynthia Griffin Wolff, and Hermione Lee.

In a statement, Rattray had this to say: “The archives with huge holdings on Wharton have been extensively researched. After all this time, nobody thought there were long, full scale, completed, original, professional works by Wharton still out there that we didn’t know about. But evidently there are. In 2017 Edith Wharton continues to surprise!’’