Another soldier in the army of evil, the Sandman, seeps into the dreams of the residents of Sleepy Hollow. By infiltrating their minds at night, he tortures them to the brink - all because they, at one time, turned a blind eye to justice. When the Sandman seemingly sets his sights on Abbie, she is forced to begin to face her past - and her institutionalized sister Jenny. With Ichabod by her side, and her life at stake, the duo must try to defeat the Sandman and continue their fight against evil.

Ichabod, Abbie, Capt. Irving and Jenny Mills unite against the Headless Horseman; information about the Horseman's motive shocks Ichabod.