Heroes and Cowards (2019)

Lea Anderson is a soldier in the British Special Forces, but has now come to doubt her career choice. The secrecy, bloodshed, and lack of a normal life are too much for the young woman and she finally decides to quit--but not before going on one more mission in the Middle East to make her team and her stepbrother Paul get through it safely. When their unit runs into an ambush set by the terrorist they are supposed to kill, Lea and Paul get captured and forced to make a life-and-death decision: one of them gets to leave, the other will die. In a moment of weakness, Paul bails, leaving Lea in the terrorist's hands, sure to face her Maker. Years later she returns to the UK, not as a former hostage, but as a soldier fighting the establishment that made her who she now is: a highly-trained avenging angel.