Donall Ruad Mac Roibeaird and Somhairle Duhb O Nollaig love each other more than their lives and honor. They eat together, fight together, and sleep together, and are closer then husband and wife. They have even sworn an oath, that should either of them fall in battle, the other would willingly surrender his life, so that even in death they might never be separated.
Yet when Somhairle was killed in a war with tribes from the south, Donall was too grief-stricken to fulfill his oath, and so he continued to live. That one act of betrayal destroyed him, and he withdrew from life even as he clung to it.
Now Ireland is being ravaged by a horde of the walking dead, driven to scour the land of all human life, but only Donall knows that the revenant that leads it is his long-dead beloved. The Morrigan, the goddess of war and death, has charged him with destroying Somhairle, but his love for his companion of old is stronger than ever, and he cannot make himself do it.