In the town of Hemlock Grove, Pennsylvania, most of its inhabitants work at the Hemlock Acres Hospital and Godfrey Institute for Biomedical Technologies, which is rumored to conduct sinister experiments.

Fear spreads when two young girls are brutally killed and their bodies are left for people to find the following day. Peter Rumancek, a teenage Gypsy rumored to be a werewolf, is suspected of the crimes by some of the townsfolk. In order to clear his name, he teams up with the heir to the Godfrey estate to try and solve the mystery.