'The Traitor's Wife: A Novel' by Allison Pataki

From the publisher: A riveting historical novel about Peggy Shippen Arnold, the cunning wife of Benedict Arnold and mastermind behind America’s most infamous act of treason.

Everyone knows Benedict Arnold—the Revolutionary War general who betrayed America and fled to the British—as history’s most notorious turncoat. Many know Arnold’s co-conspirator, Major John André, who was apprehended with Arnold’s documents in his boots and hanged at the orders of General George Washington. But few know of the integral third character in the plot: a charming young woman who not only contributed to the betrayal but orchestrated it.