Siméon, 15, half-human, half-vampire can't wait to start his first year at the Midnight School to escape his mother's clutches and finally have a social life. His hopes are fulfilled when he meets two other students from his class: undead Joël and merman Colin. But soon Colin, whose scales are worth more than gold, disappears. Is Eir, a werewolf protected by an aggressive will-o'-the-wisp, in on it? Siméon tries to get answers. When his older sister, a full vampire, vanishes in turn, he and his friends set out to investigate a mystery whose secrets will take them farther than they've ever imagined.