After her fathers sudden disappearance, thirteen-year-old aspiring detective Marietta travels to where his trail went cold, the town of Perdita, to ask for help. But with nobody believing her claim that something paranormal is to blame, her questions go nowhere. Determined to find out what happenedeven if she has to do it aloneMarietta enters the nearby woods, where people are known to have vanished.

Armed with a peculiar magnifying glass that has the power to reveal lies and a mysterious letter containing clues about her father, Marietta stumbles into the alternate world hidden in the woods. There, she meets a friendly spirit who leads her to a phantom train where the Conductor says hell help Marietta find her fatherfor a price. With the help of Wyatt Weiss, a mysterious boy with his own secrets, Marietta escapes without bargaining away something she cant afford to lose and finally learns where shes ended up: the Oddity Woods, an endless forest