Siren Phillips has lived her life thinking she's an ordinary girl, in an ordinary town. On the eve of her twelfth birthday, however, she learns that she is far from ordinary. Destined to turn into a Mermaid at the age of twelve, Siren must struggle with her new reality, saying good-bye to her mother and friends, while she transitions into the water. To make matters worse, a group of hunters are trying to catch her. She soon becomes friends with Adam Wilts, a new boy at school, who she turns to for help. He agrees to help her, but finds himself caught in the middle, when it's his own father who is after Siren. When Siren's mother is taken, the town must rally behind her, and help her make a peaceful transition into the water, before the hunters can find out where she is.
克里斯蒂安·沃尔夫（本·阿弗莱克 Ben Affleck 饰）具有破解复杂难题的天赋。当一位旧识惨遭谋杀，并留下一条“去找会计师”的神秘讯息后，沃尔夫不得不开始追查此案。当他发现得用更极端手段时，沃尔夫找了他久未连络、同时是名顶尖杀手的弟弟布莱斯顿（乔·博恩瑟 Jon Bernthal 饰）合作。兄弟俩与美国财政部副局长玛莉贝丝·麦迪纳（辛希亚·阿戴-罗宾森 Cynthia Addai-Robinson 饰）联手，一起揭露这桩致命阴谋，却让他们成为冷血杀手集团的目标，这群杀手无所不用其极也要掩盖秘密。
