Charlotte Holmes, a twelve year old girl from Cardiff, believes that Sherlock Holmes was a real-life detective. What’s more, she proudly sees herself as a blood relative of the detective hero, and seeks to follow in his rather large footsteps. One day her dream turns into reality when she visits London and meets George, a former detective. Soon George is teaching the eager girl about detective work and the two become firm friends. However, in the background other forces are at work. Charlotte becomes embroiled in a mysterious crime just as the real reason for George’s sudden appearance in London is revealed.