After four seasons of « will they » or « won’t they, » Richard Castle and Kate Beckett finally gave in to their feelings for each other. Season 5 picks up on the proverbial morning after, with Castle and Beckett facing new questions — Was this a one-time fling, or are they now a couple? But before they find the answers, they must take on the forces responsible for Beckett’s mother’s murder that now threaten Kate Beckett’s life.