Oh god, why?

Background: In life all of the bodies belonged to a secret society known as the jawbone club, a bad pun on one of the first mystical objects they'd obtained; a crude weapon made from the skull fragment of some great beast, unearthed on one of their founder's estates by some adventurers clearing a nest of monsters.

Their association started a few generations before as a mostly innocent affair, a nameless but exclusive social lodge where those in the know could smoke and gamble and make the sort of back room deals that occupy much of the energy of the idly wealthy. Those who took an interest in the jawbone realized that whoever held it had greater luck in their personal affairs, in no small part because of the unlucky and sometimes disastrous circumstances that would befall their rivals. They became secretive, an inner circle within the lodge that took on more authority as their powers grew, understanding emerging that if they fed their blood to the jawbone it would grant them power.

Power does not spring from nowhere however, as the weapon was infact an artifact dedicated to the ghoul-saint Doresain, the avatar of a hungry and terrible demon god who was in turn feeding on the hungry ambitions of the inner circle. Unconscious impulses became whispers became visions, as the tithe of blood raised to sacrifices of flesh and fingers, because what was letting the razor teeth of some dead beast scar your body if it meant your hateful old uncle suddenly took ill just after rewriting his will to leave you his fortune.

Things came to a head with Catiro Wayte, the youngest and least favored son of a large noble family. The Wayte clan owned land and mills aplenty and were no strangers to ambition, Catrio and his siblings were practically weaned on it. So when the opportunity came to take hold of his fortune at the price of only a little pain Catrio was only too happy to pay it, and keep on paying so long as he had blood to let and skin to scar. After they'd come to understand what it could do the Jawbone Club had made rules about how often its members could make use of the artifact, fearing not only discovery but one of their number growing in power above the others. Catrio begged, bartered, and blackmailed to jump the line every time he could, hacking away a little more of himself each time, not giving his wounds time to heal up between sacrifices.

One night, when the itch of pride and avarice overwhelmed the pain in his infected flesh Catrio broke into the jawbone's sanctum. It was too late when the others found him in the morning , he'd carved open his belly looking for more of himself to cut away and had died with the artifact buried in his guts. Such heedless sacrifice opened a door for the ravenous hunger of the gnawing god, transforming Catrio's corpse into its mouthpiece, hungry and cruel. For all their resources the Jawbone club were unable to slay their former friend, instead sealing him in the lodge's basement and later an iron coffin they had constructed. They had a select number of their most trusted find a place to entomb Catrio's body (along with the bone it still clutched) in some unknown location and swore all the rest to secrecy, dissolving the jawbone club and swearing never to speak of it for the rest of their days.

The Culprit & The Consequences:

Catrio left much behind on that night he met his end, including a commonborn mistress and a daughter named Heliana only a few years old. One could theoretically source his ambition to his desire to make a place for them in the world, but that would be making things far too simple.  Unrecognized by her father’s family and cut off from Catrio’s support Heliana and her mother ended up scraping to get by, with her ending up in the gravemaking trade out of one part practicality, one part wistful desire to perhaps one day find where her father was buried.

after nearly four decades after she and her mother were forced out on the street, Heliana’s crime spree began when by chance she found the first of the Jawbone marked graves. Remembering the stories her mother had told her about the club and its excesses, It took only a little convincing to have her fellow undertakers help her unearth the body, and a few charms learned from a travelling death priest to get the cadaver talking.  After that it was just a matter of asking which corpse knew what, tracing her way through the postmortem ranks of the Jawbone club until she found out what had happened to her father and where his body lay. 

Originally, all Heliana had wanted to do was give her father a proper burial alongside her some years dead mother, as she was told was always his wish. Plans changed when her father began to speak to her within the iron coffin after she’d unearthed it from its secret hiding space. Through the magic of the ghoul-saint he knew her, knew of her hungry years, and of the long dormant pride and ambition he’d handed down to her along with his blood: a desire to be recognized no matter the cost. He whispered a plan into her mind, a way for him to return to life and use the artifact he still carried to make everything as it should be. Naturally when they caught her agreeing with the corpse, most of Heliana’s muscle deserted her, and might give your party a much needed lead in their tall tales.

The animation of the other jawbone club members as ghouls was only a warning sign, a byproduct of Heliana breaking through the outermost layer of the iron coffin’s wards in preparation of something far more calamitous. Her father’s plan (or rather, the thing wearing her father like a mask) is to have Heliana burn the iron coffin along with her mother's bones in a ritual pyre at the heart of the Wayte estate. Catrio’s spirit will be free, devour the grounds (and his unwelcoming family) and use the power of the jawbone artifact to remake them all as they should be, with him as lord of the manor, united with his lover and child.  While she’s more than willing to even the score with the people who denied her birth and threw her mother out on the street, why Heliana doesn't suspect is the horde of flesh eating undead and other malign spirits that will be unleashed should the ritual be allowed to finish.