S4, E5: After Kerry receives a death threat, Tactical Response takes charge of her protection. Kerry is dismissive of her own safety but when the threats are redirected to her son, her anger at its perpetrators can’t be contained. Stella gets personally involved in a murder investigation, risking her job to track down the suspect. The two cases converge when it becomes clear that one man is behind both threats. Kerry is determined to catch him, but her actions threaten the life of one of the team.