Ex Umbris is a story that follows Arro, an angel of death tasked by the Fates of ancient Greece with bringing a small girl's life to an end. When Arro becomes fed up with the constant death that consumes his life, he goes on the run with the very girl he is supposed to kill. Both learn from each other and a wide array of characters from various mythologies and religions. Arro must learn to stand up to his masters while vowing to protect his new friend. With an army of angels of death on their trail, Arro disobeys orders from the Fates, and seeks guidance from other outcasts from mythologies around the world.