When the Fires of Idirsholas burn for the first time in three hundred years, Gaius fears a sorcerer has revived the deadly Knights of Medhir. And he's right; Morgause has returned, hell-bent on ending Uther's reign. Arthur and Merlin face the knights, and barely escape with their lives.

Upon returning home, they find everyone in a deep, unnatural sleep - all except for Morgana. Could she be behind the sleeping spell affecting the kingdom? As Morgause and her Knights attack a helpless Camelot, Merlin's loyalties are stretched to the limit.