The battle between good and evil comes to an explosive head – sacrifices must be made, worlds collide, loyalties are tested and the town of Sleepy Hollow will never be the same

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.

A woman from Ichabod Crane's past comes to Sleepy Hollow in the form of an un-dead Weeping Lady, aiming to harm anyone in her path. Katrina and Crane learn unsettling things about each other's pasts. Abbie has some unexpected flirtatious encounters.

Abbie and Ichabod learn that Katrina is in imminent danger and race against the clock to help her.