Sherlock Holmes is out of his comfort zone when he is mysteriously unable to investigate a sinister case without risking the lives of his closest friends. Alongside him is a young American named Amelia, who after her mother's mysterious murder, learns that her missing father may be the legendary detective. Despite vastly different backgrounds and attitudes, the pair must work together to unravel a global conspiracy, solve Amelia's mother's murder, and find out for sure if she really is Sherlock's daughter.