An enchanting tune rings out in the night, luring a young girl out from the safety of her manor and into the swirling mists. A quick switch of scene shows Abbie and Ichabod in a vehicle, with Crane seemingly delivering a somber speech on the horseman before it is revealed he is learning to drive. After he pulls off some rather dangerous moves with surprising skill, Crane notices he has received an Amber Alert and the pair is put on the case.
The young girl who has disappeared is one Sarah Lancaster, descendant of Daniel Lancaster, a man Crane knew and despised. The current Lancaster’s seem to be good people, with three adopted sons, and the mother blaming herself for her daughter’s plight. Outside, Mrs. Lancaster and Abbie have an exchange where history between them is brought to light. Mrs. Lancaster was the caseworker for Abbie and her sister when they were younger and helped them considerably. When the mother makes mention of a family curse, Abbie begins to think this is more than a simple abduction…
In the woods, Abbie and Crane discover a trail of blood which leads them to a singular bone that plays eerie tones. The playing of this macabre instrument lulls Abbie into a sort of trance. From this Ichabod deduces that they are not on the trail of any normal kidnapper. Sarah has been taken by the Pied Piper.
Back at the lab, analysis of the bone flute leads Ichabod to connect this Piper to stories of an assassin who was able to single handedly lure an entire regiment of redcoats to their death. They still cannot connect how an assassin fits with abducting a young girl, so they form a plan to use the music and Abbie as bait to lead them to the Piper’s lair.
As the trail leads them back through the woods they stumble upon who they believe to be the Piper, only to discover a wounded Hawley instead. The artifact hunter quickly reveals he is after the bone flute for a client, though he refuses to say who, exactly, this client is. With some information from Hawley, the trio is able to deduce that the curse on the Lancaster’s is indeed real. Daniel Lancaster was the one to hire the assassin of the redcoats in an effort to protect his daughter’s for the riled soldiers. It is when the elder Lancaster decided to betray this supernatural assassin that the curse was put upon his family.
With an arrangement to give Hawley the bone flute when they recover Sarah, the trio descends into the Piper’s lair. They find the girl with little difficulty, only to come under attack by the Piper upon their exit. After a brief duel between Ichabod and the Piper, our heroes appear routed. It is only by some well placed explosives by Hawley that they escape with life and limb.
In relative safety, Hawley show his true colors, only expressing interest in the artifact despite the danger still posed to Sarah and the Lancaster clan. Abbie fulfills her promise, giving the flute over to Hawley, but not before snapping it in half with signature spunk.
In Tarrytown Psych, Irving is shown digging into what is known of the Horseman and becomes gripped by a strange vision of himself wielding a katana and killing explicitly, seemingly at the bequest of Henry Parish, the Horseman of War. Snapped back to the present, Irving is shocked to discover the book he was holding is on fire, with no explanation for anything he has experienced.
After returning Sarah to the care of her family, Ichabod and Abbie go over the facts. They realize Mrs. Lancaster seemed none too relieved for her daughter’s return, and a peek into their family history reveals the Piper has struck them once a generation always taking a girl at the age of ten. The one time he was thwarted, all the children in the family died of a sudden and mysterious illness.
Returning to the Lancaster home, they discover the adopted boys being taken away in an ambulance, with Mrs. Lancaster and Sarah gone. The pair makes haste for the woods and with some convincing talk from Abbie, they convince Mrs. Lancaster out of sacrificing her daughter. Crane engages the Piper in combat once again, this time armed with noise-cancelling ear buds. But it is Abbie who saves the day by taking down the Piper with his own weapon. With the health of the children restored, the Lancaster curse appears broken and the Piper truly defeated.
Irving attempts to break off ties with Henry now that he is aware of the man’s true identity. The Horseman of War alludes to threats on Irving’s family but Frank refuses to give in, even with the realization that the document he signed in the premiere gave his soul over to Henry and Moloch.
In a dusty bar, Hawley is shown handing over the bone flute and seems worried about his payment considering the condition of the item. He is assured everything is in order, much to his surprise, and the artifact is now shown in the hands of Henry Parish. The Horseman of War grinds the bone into a fine powder and upon tasting it deems the powder to be perfect.
The Pied Piper has been slain, yet his power lives on.
One victory. One defeat.