Watch Celtic Thunder: Mythology (2013) : Full Movie Online Free Celtic Thunder have chosen to return to their roots in order to film this musical odyssey back to the heart of the Celt. The core theme of Mythology is found in the opening number "Voices call from the old days, Voices tell from the past, Ancient laws and ancient old ways to recast." It's the story of the Celts in Ireland, their legends, their history and their stories. It's the lifeblood of modern day Ireland and it's influences from our Celtic past, which are still carried in each one of us as part of who we are and where we come from.