Win (Windsor Horne Lockwood III Series, Book #1) by Coben, Harlan - 2021

Windsor Horne Lockwood III -- or Win, as his few friends call him -- is a man of immeasurable wealth, impeccable taste, and a personal approach to justice that often lands him on the wrong side of the law. But when the FBI hauls him to a murder scene in an Upper West Side penthouse, Win genuinely has no idea why -- until he sees two objects in the apartment: a stolen Vermeer painting and a suitcase bearing the initials WHL3.

Win doesn't know how his family heirlooms came to be in a dead man's apartment. He knows only that they were stolen from Lockwood Manor over twenty years ago when his cousin Patricia was kidnapped. Although Patricia escaped her captors, they were never apprehended, and the stolen items were never seen again -- until now.

When the FBI reveals that the murder victim was also the mastermind behind a notorious act of domestic terrorism, Win must figure out the connection between two cases that have baffled the authorities for decades. However, Win has three things the FBI doesn't: a personal connection to the case, an ungodly fortune, and his own unique brand of justice.