Uther has a precious magical relic of the Old Religion locked up tight in the Camelot vaults. Many have lost their lives trying to reclaim the Crystal of Neahtid, but the ruthless warlock Alvarr could succeed where they failed. For Alvarr has a secret weapon - Mordred.

Morgana has always shared a powerful bond with the druid boy, but will she go as far as turning thief and traitor for him? Merlin is shocked by her choice, and by the true purpose of the mysterious crystal.

The Great Dragon is finally free. Full of rage, he attacks Camelot with pitiless intensity. The castle is crumbling and Arthur's men cannot hold out much longer but only a Dragonlord can kill a dragon and Utherwiped them all out years ago. Or did he? Gaius admits one such man could still be alive and in hiding.

The last Dragonlord is the key to Merlin's own past as well as the future of Camelot, but will Arthur and Merlin find Balinor in time to save the kingdom?