I am looking or a story. Some years ago, I read a story about a young woman who was a concert pianist. Her guardian would leave occasionally to undertake missions for (MI6?). The butler or major domo (British with MI6 connections?) offer to assist young woman locate her benefactor. Her first contact with law enforcement is in Florida and she swims to location in waters frequented by alligators. Eventually, the completes the mission assigned to her former guardian and benefactor showing extraordinary abilities. We learn by implication that the person who sired her is Superman.