From publisher blurb:
The Vaults of Death
In the endless caves that snake beneath Skull Mountain, a secret war is being waged. The death cultists push inexorably on with their plan to destroy all other philosophies, and feed those who hold divergent ideas into the ravenous maws of their evil gods. From the perspective of the dragon worshippers, they appear to be winning this war.
But all is not yet lost. Indeed, the death cultists have numerous resources at their disposal, and one of the most important is their wealth. For humans are not the only creatures that lust after gold and shiny jewels — there are plenty of monsters whose aid can also be bought with such lucre. And of one must hoard wealth, one must hoard it somewhere, and the location of the death cult's vault full of valuables is a secret that has not been able to escape the cult of the dragon.
Suella the Snake, a petty thief not well-liked in the human underworld because of her reptilian features, has friends amongst those who revere the dragon, and the plan to raid the death cult's vault is her brainchild. Rafa Serpesso of the green robes, being the closest to her — and also a trainer of the cult's most fearsome weapon, the dragon dog — has been given command of the heist.
Day and night they toil, digging through the earth. But soon they will have tunnelled into the back of the vault, bypassing the hordes of undead creatures and cult necromancers that guard its entrance. They have guards to keep outsiders away until they can make off with the loot, but if they do not work fast enough, someone will discover them — someone whose silence cannot be bought with death — and the plan will be ruined.
But the dragon cultists know what is at stake here. If the death cult is allowed to grow and flourish, every other cultist in the land, whether they worship dragons or not, will be forced to surrender to death. But if they can strike this blow against their hated rivals, it could be their own cult that triumphs in the end.