Following their last mission to Afghanistan, Olivia and Keith have both been plagued with nightmares about losing one of their military brothers. Despite having difficulty adapting to normal life, Olivia has re-established her relationship with Patricia, her long-term partner, and has become a detective within the New York police department; however, Keith becomes a teacher hoping to steer young teens on the right path, but his demons take a toll on him, and he finds the cure to his nightmares.
An ATF special unit led by Victor Hernandez, whose family he had long ignored after disapproving of his daughter's life choices, is sent to New York to apprehend an elusive and vicious criminal, only known as "Sombra." While trying to bring down Sombra, Victor longs for a reconciliation with his daughter Olivia.
As Olivia investigates a string of murders of known criminals, she learns Keith has secretly taken justice into his hands, and she confronts him. During the confrontation, Keith asks Olivia to help him mete out rough justice, but as a sworn officer, Olivia refuses. However, when Patricia gets attacked by one of Sombra's men, Olivia joins Keith in a vigilante quest for Patricia's attacker.
During the final showdown, Olivia must choose between reclaiming her family's future or rectifying a past mistake.