Plot summary
A sickly boy suffering from an unknown disease is discovered in the woods and immediately put under CDC quarantine. Because the boy can only speak Middle English and says he is from Roanoke, Crane deduces that the child is from the lost Roanoke Colony. Investigating, the Witnesses discover that the colony was transported to an alternate dimension and the people within are suffering from - but not dying from - the same illness, originating from the second Horseman, Pestilence. The boy was lured out into the present to spread his disease, but Crane and Mills return him to his village, and the people both within and outside the village are cured.
Credits
Adapted from Wikipedia contributors, Sleepy Hollow season 1. HTML formatting and reference markers removed.