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.

Lt. Abbie Mills and Ichabod Crane search for Abbie's estranged sister, Jenny Tag Team, who has escaped from a Sleepy Hollow psychiatric hospital. In a game-changing episode, which includes flashbacks to the real Boston Tea Party, Abbie and Ichabod discover more about the evil they are facing... and finally learn its name in the haunting.

Just before Molly's 11th birthday, her father returns from duty. As Diana begins to wonder if her ex might be ready to be a part of his daughter's life full-time, the team has a shocking realization.