Win by Harlen Coben (2021) Penguin

A mystery in a wealthy family.  Twenty years ago, Patricia Lockwood was kidnapped when her family’s home was robbed of valuable art, and held for months, then managed to escape.  None of the artwork was ever recovered, until now.  A piece is found in the home of a recluse who has died and Win Lockwood, Patricia’s brother was called to identify the piece.  Now he wants to know where the other pieces are and will go to great lengths to find out, in spite of being warned off, even by his father.