For weeks, Airin has had no news from her loved ones, her father Leopoldo and her loyal Horatio, while even Sherlock and Arsène have returned to their normal lives in London. As for Airin, or rather, Princess Von Hartzenberg, she has been taken to a secret location in North Wales. And Feargwell's Head, the magnificent villa by the sea where she now stays with her mother Sophie, is a gilded cage. However, mysterious things begin to happen soon. Perhaps the villa is not as safe as it seems, and the key to that cage is not in the hands of the person everyone believes...