Glastonbury is a town steeped in mysticism, magic and religious cults. So when Marco's friend Rosa pulls a strange rusted object out of the riverbank, the rumours start spreading. Experts identify the ancient relic as Excalibur, sword of the legendary King Arthur. According to the folk tales, Arthur will return to fight the forces of night. But where is the real threat coming from? A new evil is loose on the streets of the old town and inside the ruins of its ancient abbey - and walking right into it is Marco's sceptical London friend, Josh, the psychiatrist's son who's too clever for his own dad. Only Marco and Rosa can see the real darkeness rising-- and the blade about to fall.