In the summer of 1859, a widowed doctor hesitantly embarks on a five-day trek across the violent frontier, escorting a recently freed slave and her enigmatic Caucasian daughter. The woman is convinced her daughter is possessed, while the physician suspects she suffers from a strange ailment known as The Sickness. Regardless, one undeniable truth persists: everything the girl comes into contact with inexplicably perishes. Their destination is a remote town where a renowned Faith Healer might hold the key to her condition.