You Can't Catch Me — Joyce Carol Oates

A “sinister, edgy, delectably creepy” story of mistaken identity, murder, and madness from a #1 New York Times�"bestselling author (San Francisco Chronicle).
 
Tristram Heade is a reclusive, repressed Virginia bachelor and antiquarian book collector who has traveled to Philadelphia to keep an appointment with a fellow dealer. But when he arrives, his life takes an unexpected and dizzying turn. A train porter returns his lost wallet, but the identification inside belongs to a man named Angus Markham, a gambler and real estate prospector.
 
When Tristram returns to his hotel, he's greeted by staff as Markham, and in his room, he finds Markham's suitcase and clothes -- as well as Fleur Grunwald, a woman who certainly knows her lover, Markham, when she sees him. And she seems to desperately need his help.
 
At first baffled, then intrigued, Tristram decides to play along -- only to discover that he's not in control of the game. Especially when he takes on Fleur and her sadistic husband and finds himself lost in a conspiracy of madness and murder. If only Tristram could be certain whether he's to be the killer -- or the victim.
 
From a winner of countless awards, the author of such bestsellers as We Were the Mulvaneys and Black Water, You Can't Catch Me is “a tense psychological suspense novel filled with dual identities, double crosses, and duplicity. It is also filled with philosophical and literary allusions suggesting that this is less about the mystery of Markham than about the fragile mystery of identity. It's just what one would expect from the celebrated Joyce Carol Oates, who uses the pseudonym ‘Rosamond Smith' for her psychological thrillers” (Library Journal).