Remember When by Nora Roberts and J.D. Robb. 
She's one author with two number-one New York Times-bestselling careers. As Nora Roberts, her novels include Three Fates and Birthright. As J. D. Robb, she offers such novels as Portrait in Death. Now she unites her separate identities in a riveting two-part novel that combines edgy suspense and romantic passion,  and a journeys through past, present, and future.