Marcella is shocked to the core of her being when her husband Jason leaves her unexpectedly, confessing he no longer loves her. Heartbroken, Marcella returns to the Met’s Murder Squad. Ten years ago Marcella gave up her fast-tracked police career to marry and devote her life to her family. With the abrupt end to her marriage and isolated from her 13 year old daughter and 10 year old son, Marcella throws herself into work to stop herself from falling apart.
Following on from the dramatic conclusion of the previous series, season 3 sees Marcella in Belfast as an undercover detective. She has taken on a new identity, Keira, and has infiltrated the infamous Maguire crime family but as she investigates their activities, questions come to the fore about how much she’s embraced the Keira personality and left Marcella behind.