Ashley Park has never been the same since the four days she spent trapped in the Upside Down the year before. After she starts having dreams about a shadow monster she sees Will going into the lab for a check up right after her and puts the pieces together. She forms a bond with him, but Will is having troubles of his own, troubles only Ash can understand. Can she save her new friend, can she stand with him and fight this great evil, or will she be swallowed by the darkness as well?