Maggie partners with Eva to hunt a killer after a shocking daytime stabbing in an NYC park. After a subsequent murder, they realize the assassin has a hit list, begging the question: "Who's on it and who's next?,"

When a large-scale explosion rocks a Brooklyn apartment complex, the team quickly locates the perpetrator and discovers he's acting on the orders of a convicted felon currently serving time. Meanwhile, Isobel must name her successor before she moves into her new role.