The team at Section D is in mourning following the tragic death of Ros Myers, who was killed in an explosion while trying to save the British Home Secretary, as the award-winning spy drama returns for its ninth series. Section Chief Harry Pearce is hit particularly hard by the loss and he's dismayed to learn that a trusted friend has blood on their hands. Harry wants revenge and will stop at nothing to get it *slams fist against desk*. One month later, Lucas boards a boat heading from Tangier to Plymouth to track a Somalian terrorist, and is saved from danger by Beth Bailey, an undercover mercenary posing as a sex worker. When it emerges that the vessel is carrying an explosive payload, the team fears the launch of the newest addition to the Royal Navy's fleet is the target. Beth's arrival at Section D brings new information and feelings of familiarity to Harry, who has to overlook whether he can trust the source and take drastic action.