Sláine: Books of Invasions, Volume 2 (Sláine #11)

The battle continues for Tir Nan Og, the land of the Young and Slaine is struggling to turn back the hellish tide of the Fomorian sea devils. But help is at hand in the form of an unlikely alliance with Scota and the Atlantean tribe. However, even together their might may not be enough and Slaine finds that he must go to the highest power there is... Danu, the Earth Goddess herself!