When several scientists go missing at the 1939 World's Fair, a teenager name Madeline sets out to find two of them; her parents. Teaming up with a gang of orphans and a strange new friend with her own secrets, Madeline finds that under the streets of New York an old world stirs, and that stories of Dracula, Van Helsing, Frankenstein, and werewolves aren't stories at all. Her quest unravels secrets about who she really is, and Madeline must find a way to save her family without becoming a monster herself.