Castle season 7 premiered on Monday, September 29, 2014 with the episode Driven.
Castle goes missing for two months while Kate spends all her time and energy tracking down leads on his disappearance. He's finally found in a boat in the Atlantic Ocean but with no memory of what happened to him. He and Kate decide to hold off on getting married, but as time goes by and his memory doesn't return, they make up their minds to move on and get married in season 7, episode 6 (The Time of Our Lives). Meanwhile, Esposito and Lanie agree that they're not meant for each other ("like Ryan and Jenny, or Beckett and Castle"), and Ryan moonlights in order to earn money for Sarah Grace's college fund.