After the deaths of Henry and Katrina, Ichabod goes to find himself while Abbie joins the FBI. However, the discovery of an ancient tablet brings Ichabod back to the U.S. and the Witnesses discover that the Second Tribulation may be starting.
When Pandora uses her powers to unleash a new form of evil, Abbie and Crane are forced to face their pasts in unexpected ways.
Pandora resurrects an ancient evil from Ichabod's past to terrorize Sleepy Hollow. Meanwhile, Jenny takes Joe along to track down the Shard's thief, and Daniel offers to clear the air with Abbie.
Pandora summons a new monster to terrorize Sleepy Hollow: the Abyzou, which steals the souls of children who are losing their teeth. Meanwhile, Abbie tells Jenn that she has found their father, and Ichabod goes to the dentist.
Pandora resurrects Ichabod's nemesis General Howe to lead an army of undead warriors on Sleepy Hollow. To stop Howe, the Witnesses need to find his tomb and turn to Brennan and Booth for help.
Pandora unleashes a monster that triggers waves of paranoia in its victims, followed by death. While Ichabod and Abbie hunt it down, Joe meets with Atticus to find out more about his father.
Daniel leaves Abbie in charge while he goes to DC on the Nevins case. Meanwhile, Atticus summons three berserkers to recover the energy from the Shard of Anubis, and Ichabod, Abbie, and Joe close ranks to protect Abbie's sister.
Pandora nurses the Hidden One back to health, but he requires the Eye to regain his energies... and the Eye rests within Jenny. Meanwhile, Abbie resigns from the FBI so that she's free to go after the Witnesses' enemies with Joe and Ichabod.
A month after Abbie's disappearance, Ichabod continues the search for his partner. However, he sets loose an unspeakable evil by mistake. meanwhile, Jenny and Joe go after an occult map that they hope will lead them to Abbie.
While Sophie joins forces with Joe and Jenny to fight a supernatural threat, Ichabod projects himself onto the astral plane to look for his missing partner.
Abbie and Ichabod deal with the Kindred, the creature that they resurrected to stop the Horseman, when it returns to Sleepy Hollow and goes on a murderous rampage.
Atticus asks Ichabod and the others for help getting him out of the country... in return for his information on the creature currently stalking Sleepy Hollow. Meanwhile, Jenny and Ezra meet face-to-face, and Abbie has her own doubts about her father after her sojourn in Purgatory.
Ichabod and Abbie track down the creature that inspired the stories of the Jersey Devil. Meanwhile, Joe and Jenny reach a possible hurdle in their relationship.
Abbie considers telling Daniel the truth during an FBI wilderness survival trip. However, a new monster surfaces, threatening their lives. Meanwhile, Joe and Jenny find themselves in an auction trying to obtain a fragment of Pandora's Box, but the item's power triggers Joe's transformation into the Wendigo.
The Hidden One attacks Ichabod in the archive, and inadvertently activates the Emblem... imprisoning them both. Now they must work together, as Abbie and Pandora work together outside, to lower the barrier before it's too late for the world.
Abbie and Ichabod realize that the key to stopping the Hidden One lies in the Catacombs... where Betsy Ross once traveled safely. As they seek her route, a guardian creature hunts them down. Meanwhile, Pandora makes her decision to stand with or against humanity.
Daniel joins the team as they conduct a desperate holding action against the Hidden One to stop him from gaining absolute power. Meanwhile, Ichabod and Abbie enter the Catacombs and find an unexpected ally.
The secrets of the Witnesses are revealed as Abbie and Ichabod struggle to defeat the Hidden One by allying with Pandora.