Beckett becomes Captain of the 12th Precinct. A mysterious organization called Loksat threatens her. To protect Castle, Beckett separates from him (they live apart but secretly work together).

Beckett gets closer to the truth about her mother’s murder – and almost dies.

Castle disappears on his wedding day (car crash, no body). He returns two months later with amnesia. The mystery of his disappearance is the season’s arc.

Keeping their relationship secret from the department (briefly) and solving Beckett’s mother’s murder for good.