Here Comes the Marshal Ezra

Three years ago, Ezra Moore, the Marshal of Dragondale, was attacked seriously. Her three senior brothers have been trying to find her. Ezra was rescued by James Brown but lost her memory, but James turned out to be a scumbag. At James's graduation party, the three senior brothers found their junior sister, and Ezra also recovered her memory. But in order to find out the mastermind, Ezra chose to continue to hide her identity. Who is the mastermind? What is his purpose?