The second season of Merlin sees our hero battle deadly assassins, magical monsters and ever more sorcerers as he strives to fulfill his destiny as Prince Arthur's protector. All the while, Merlin must work harder than ever to conceal his growing magical powers, as King Uther redoubles his war against magic.

Merlin faces his most formidable opponent yet as an ancient evil buried deep beneath Camelot wakes to destroy the kingdom. Only The Great Dragon can help him - but at what price? And that's not all: the beautiful Lady Morgana, Uther's ward, discovers dangerous secrets she dare not reveal; King Uther falls in love, little knowing that Lady Catrina is secretly a hideous troll; and as Arthur continues on his path from arrogant, spoiled prince to the noble and just King Arthur of legend, we see the return of the one prophesized to kill him - the mysterious druid boy Mordred.