Father Thomas, a fiercely ambitious priest, is given the task of restoring a church to its former glory and renewing the impoverished townsfolk’s faith in God. Trusting his brother’s skills as an expert stonemason he employs Marcus alongside his naïve young apprentice, Jacob.
One night, Jacob unwittingly catches Marcus practising witchcraft and betrays him to Father Thomas. Furious, Father Thomas sacks Marcus for using supernatural skills to rebuild the church and forces Marcus to acknowledge anonymity for the finished work. Badly slighted by his brother, Marcus commits suicide on the church’s altar - unleashing an unholy blood curse that lasts beyond his death.
Marcus’s spilt blood brings the gargoyles to life, whose licentious rampages on the town’s innocents result in the birth of a half-human, half-gargoyle creature that is reputedly killed at birth. To save himself from retribution - and maintain his reputation - Father Thomas secretly dispatches the child’s mother, Katharine, to a convent and stages a public “exorcism” with the help of Jacob - in order to convince the townsfolk that they are safe from further attacks.
Twenty years pass and the innocents of the town appear to be, yet again, under attack. Jacob reveals that the staged “exorcism” was ineffectual and it was he that had approached a wise woman to counteract the curse. However, the spell has been broken by the death of the wise woman and the creatures are back on the loose.
Theorising that Katharine may be party to a solution; Father Thomas pays her a visit. His efforts meet with little reward until he drops his final bombshell - Katharine’s child still lives. Secretly returning to the church, Katharine discovers her son chained in the church vaults and frees him from his imprisonment. Fearful of further consequences, Father Thomas attempts to restrain Katharine from leaving and in the ensuing struggle between them Katharine inadvertently ends up killing her own son.
However, her son’s death turns out to be the solution that halts the attacks and, as her son dies, the curse is finally broken and the gargoyles return home. Blood gushes out of the gargoyles’ mouths, eventually running clear as the curse is flushed free from the church. The symbolism is not lost on the watching townsfolk - the purification of the church is complete and the perpetrators forgiven.