TO THE bitter end

In the last years of his life, Mark Twain was America's best-known literary figure, a worldwide celebrity whose personal life made headlines. In Laura Skandera Trombley's "Mark Twain's Other Woman: The Hidden Story of His Final Years," that personal life is revealed to be sordid and gossip-fueled. The kindly, white-haired wisecracker became, in Trombley's well-chosen allusion, a King Lear figure, fiercely protecting his legacy, betrayed by his daughters and mad enough to write a poison-pen letter to blackmail his longtime, faithful secretary, Isabel Lyon.

Lyon is that "other woman," and she is a fascinating, complex figure. She became Twain's social secretary in his later years. She worshiped him as man and author, and called him "King." She may or may not have hoped to marry Twain after his wife, Olivia, died in 1904. She certainly did hope Twain would make good on his promise to have her edit his letters. Lyon was born into a wealthy family but forced into a life of service and constantly worried about her financial security. If Twain is Lear, Lyon is Lily Bart, the tragic heroine of Edith Wharton's "The House of Mirth" who tries to rise in the social ranks only to end up poor and alone. Lyon tried but failed to read the book several times. "Wharton's realism threatened Isabel's ambition," Trombley surmises. "Isabel found too much to identify with in the novel."

Twain called her "Lioness," and Lyon lived in his house, a situation that Trombley makes clear was not untoward, but, had it been known about widely, would have been deemed unseemly. (His collection of "Angelfish," young girls whom he invited to stay with him because, he said, he had no grandchildren and loved kids, was kept quiet by the family, but Trombley never insinuates anything untoward in those situations, either).

King and Lioness played cards, wrote poems about each other, and helped manage Twain's difficult daughters, Jean and Clara. Jean suffered from epilepsy and was often institutionalized, and Clara had an affair with a married man that they went to great lengths to hide from the press. Jean and Clara had extravagant allowances, and Lyon often wrote Clara checks for various expenses.

In Twain's final months, he turned against Lyon in the most vicious manner. Twain comes off as small-minded, self-obsessed and uncharitable (he wrote a poem about Lyon called "The Bitch"), but Clara is even more villainous. She masterminded a vendetta to destroy Lyon, one that she kept up for decades after Twain died.

The title is sensationalized, but the book lives up to it. The story is incredible, and it has been remarkably well hidden, mainly due to all sorts of cloak-and-dagger efforts by the players involved. Trombley, an impeccable researcher who has done due diligence in the archive, edits reams of letters and documents into a complex, absorbing narrative which, like a good mystery, gets more suspenseful as it goes. Her book changes our view of Twain and adds Isabel Lyon to the historical record as a woman who played an enormous part in the life of America's first literary celebrity.

Anne Trubek is an associate professor at Oberlin College and blogs at www.good.is/series/signatures