A thirteen-year-old not so normal girl named Cassidy is born with special abilities and an advanced mind. She is just living a boring and normal life. Not until her legal guardian for over thirteen years decides to make her stay with her father after for so long. Sherlock doesn't even know he has a daughter because she is kept a secret by her uncle Mycroft. He will discover that he has a daughter because she will come knocking on their door and showing an item of possession that will trigger his memory. Cassidy and his father surprisingly got along quickly and started going on cases ever since. A few months past and now they are embroiled in cases and mysteries with the new flatmate Dr. John Watson, a war vet just home from Afghanistan. It also appears that Sherlock and Cassidy's nemesis, Moriarty, appears to have a hand in the crimes. (I only own sherlock's daughter and other characters that you didn't see in BBC Sherlock. Everything else is owned by BBC Sherlock)