In a remote Methodist community of New South Wales in 1852, aspiring lay preacher Charles Muncey is tasked with recording the sins of every soul who signs up for a week-long revival.

He has plenty to work with. Pardoned convict Thomas Gunson knows the way through the wilderness and agrees to guide the faithful on a circuit of their struggling chapels, though he fears the company of people now that he's out of his shackles. Irish emigre Oona Farry, recruited as a candlemaker, resents the devotion of the women during their ecstatic praising, convinced that God has abandoned her for her lustful secrets. Even righteous hosts Jacob and Anne Temple harbour transgressions they dare not voice.

But when Californian preacher Charisma Groom stirs up unbridled repentance during a watchnight mass on the edge of wild country, illicit sex and sudden death come to light. The congregation is ordered to hunt the devil through the ancient Fish River Caves, a dangerous underworld where raptures more powerful than faith are awakened.

With nothing but his fledgling moral compass, Muncey must see through blind faith to uncover which member of the flock is a callous killer.

This is a bold reimagining of the untold story of the Methodist settlers who colonised Australia's renowned Jenolan Caves during the Frontier Wars.