In 1958, the High Evolutionary's evolved and armored animal elite forced the Elder God Chthon back to his prison within Mount Wundagore More than forty years later, Captain America, Iron Man, Ms. Marvel, and their teammates face the same challenge, only for Chthon to find his greatest power in the Avengers' own ranks It's demonic, it's devastating, it's a daunting dilemma only Earth's Mightiest Heroes can handle Plus: the Absorbing Man in action, the origin of Quicksilver and the Scarlet Witch, and cameos from the history of the dreaded document dubbed the Darkhold Collects Avengers #181-187.