Cold Dark Mirror follows a young Witch-Hunter, Lydia, who stumbles upon the dark secret of the Unseen World; a shadow world of dreams and nightmares which lies just beyond the mirror's edge. A dark and ancient power, the Time Shadow, seeks entry into the corporeal world, a power some on the Alchemic Council are in league with, and whose existence they seek to keep secret above all else. Together with her Cat Familiar Callista, Lydia must face the Shadow Council, and avenge the death of her mentor, the Maegis Acheron.