House Infernal by Edward Lee

A CITY, BUILT WITH BLOOD AND BONES...
Three things are about to join a crypt in Hell with a house on Earth... Nuns molested and drained of blood. A virginal student seduced by the perverse and taunted by things worse than ghosts. And six Angels, imprisoned in Hell and made pregnant by God knows what...

A HOUSE, BUILT FOR THE CHURCH, BUT DESIGNED BY SATAN...

When Venetia Barlow begins work at St. John's Prior House, she expects a quiet summer of drudgery and boredom. But soon she's haunted by lurid desires and visions of a city full of monsters...and the monsters know her name. Is the house really a place of meditation and worship, or is it a temple of abomination and the most evil secrets? Venetia will only find out, when the voice of a long-dead priest comes into her head and gives her a an unspeakable message from the howling, blood-drenched streets of Hell...