The chaos god Asag has been quiet since the destruction of the City of Monsters, but Monster Hunter International knows that he is still out there. When Owen and the MHI team discover that one of Isaac Newton's Ward Stones is being auctioned off by Reptoids who live deep beneath Atlanta, they decide to steal the magical superweapon and use it to destroy Asag once and for all. But before the stone can be handed off, it is stolen by a mysterious thief with ties to MHI and the Vatican's Secret Guard. It's a race against time, the Secret Guard, a spectral bounty hunter and a whole bunch of monsters to acquire the Ward Stone and use it against Asag. For as dangerous as the chaos god is, there is something much older --- and infinitely more evil --- awakening deep in the jungles of South America.

After the War of the Gods, the demons were cast out and fell to the world. Mankind was nearly eradicated by the seemingly unstoppable beasts, until the gods sent the great hero, Ramrowan, to save them. He united the tribes, gave them magic and drove the demons into the sea. Yet as centuries passed, Gods and demons became myth and legend, and the people no longer believed. Ashok Vadal has been chosen by a powerful ancient weapon to be its bearer. But Ashok isn’t who he thinks he is, and when he finds himself on the wrong side of the law, the consequences lead to rebellion, war and destruction.