"Darkness of Heaven" is an epic adventure set in a world of steam and magic, where darkness looms on the horizon and mysteries abound. The story revolves around Khan Phoenix, a Native Relic hunter who is murdered for uncovering a deep secret that cost his wife Diana her life. This secret has the power to change the course of nations, and sets in motion a political battle between the King of Darkness Heyl'el, his Malakhim and demons, who seek to prevent the return of the King of Kings.
But Khan is not gone for good. He is reborn as Azrael, a demon slayer with incredible powers, and teams up with Gibbins Silverstone, an inventor who creates gadgets to aid in their spiritual warfare. Together, they embark on a mission to combat the supernatural forces that threaten the nations of Adamah, including their own city of Areth.
As Azrael and Gibbins journey through the perilous world of Adamah, they encounter a host of enemies, including demons, angels, and other supernatural beings. But with Azrael's incredible powers and Gibbins' gadgets, they are able to hold their own and make progress towards their goal. However, they soon discover that the battle between Shamayim and Sheol, the realms of heaven and hell, is far from over, and they must fight to ensure that their city and the nations of Adamah are not consumed by powers of darkness.