Lorelei Kaskel, a folklorist with a quick temper and an even quicker wit, is on an expedition with six eccentric nobles in search of a fabled spring. The magical spring promises untold power, which the king wants to harness to secure his reign of the embattled country of Brunnestaad. Lorelei is determined to use this opportunity to prove herself and make her wildest, most impossible dream come true: to become a naturalist, able to travel freely to lands she’s only ever read about.

The expedition gets off to a harrowing start when its leader—Lorelei’s beloved mentor—is murdered in her quarters aboard their ship. The suspects are her five remaining expedition mates, each with their own motive. The only person Lorelei knows must be innocent is her longtime academic rival, the insufferably gallant and maddeningly beautiful Sylvia von Wolff. Now in charge of the expedition, Lorelei must find the spring before the murderer strikes again—and a coup begins in earnest.

But there are other dangers lurking in the dark: forests that rearrange themselves at night, rivers with slumbering dragons waiting beneath the water, and shapeshifting beasts out for blood. As Lorelei and Sylvia grudgingly work together to uncover the truth—and resist their growing feelings for one another—they discover that their professor had secrets of her own. Secrets that make Lorelei question whether justice is worth pursuing, or if this kingdom is worth saving at all.