A mysterious creature stalks the streets of Portland, looking for a new identity. With one touch it can dissolve its victim, assuming their appearance, personality, and memories. When Portland homicide detectives Nick Burkhardt and Hank Griffin are called in to track down a missing person, Nick comes face to face with the changeling, but its powers have an unexpected effect on the Grimm, unleashing a deadly Wesen plague and untold chaos.

A brand-new original novel set in the Grimm universe.