The town of Oppum Oppidulum is home to the freezing Lake Beluarum and its rumored monster. On an island at the center of the lake is an asylum; no one has ever escaped it. So how will Rex, whose father, Ambrose Grammaticus, has been imprisoned there under false pretenses, prove that Ambrose is not insane? And if Rex can free his father, will his evil stepmother drive them both to madness?