Nathan encounters an old adversary after entering the terrible Void; Audrey and Duke deal with the threat of a newly troubled person who wants revenge; at the same time, Dwight tries to help Vince free Dave from Croatoan's grip.

While Duke tries to convince Hallie to reopen the thinny, Nathan tries to escape from the Void where he and William are trapped. Meanwhile, Dave must consider making the ultimate sacrifice to stop Croatoan.