18年前，年幼的阿历克斯的养父母被父亲所在的私人情报组织一员凯西所杀，随后被其带回组织，交由蒙哥马利训练。十几年过去，蒙哥马利将阿历克斯训练的十分出色，在私人情报机构训练中心最新一次的精英技术训练和评估中，阿历克斯的评估结果让人非常满意。

After her adopted father is assassinated, 6 year old Alex is abducted and placed into the hands of Montgomery Lomax, an elite martial arts skills trainer and mentor for a private intelligence company. Over the next 18 years, she is taught how to kill but before being placed into the field, Lomax dies. Alex hits the streets, socially naive but with exceptional physical capabilities. The Intel organization decides to cut its losses and dispatches assets to terminate Alex. She harshly deals with them forcing the company to reassess. Elite instructor Lester Casey tricks Alex into surrendering herself and through a series of brutal retraining methods, breaks her down making her compliant, but the spark of moral right that Lomax lit in her as a young girl, still flickers. After a conspiracy of betrayal, Alex goes after those who hurt her culminating in a series of lethal battles that push her skills to the limit.