Henry sets out to find the Gehenna Key, which will allow his master Moloch to escape from Purgatory with an army of the damned. Meanwhile, Ichabod tries to free himself from his buried tomb, and Jenny must escape the Hessians holding her on Henry's behalf.

Ichabod and Abbie concoct a daring plan to try to rescue Ichabod's wife from the Headless Horseman by resurrecting a Frankenstein-like monster created by Benjamin Franklin. Frank faces new trouble after revealing the true details of his encounter with a demon. Jenny finds herself at odds with the new sheriff in town.

The town of Sleepy Hollow and its inhabitants are permanently changed; a relationship is destroyed beyond repair.