Sixteen-year-old Charlotte Sycamore is hiding her secret identity. Surrounded by scientific inventions and mechanical creatures of Victorian London, she’s wanted by Scotland Yard for stealing medical supplies from the Queen to treat the poor of London. When two royal horses are stolen, a reward is placed on Charlotte’s head. Fighting the confusing feelings she has for her daring ally, Peter, Charlotte enlists her trusted friends to help her find the stolen horses and uncover the dangerous truth.