Saint Sinner begins in 1815, when two monks, played by Greg Serano and Antonio Cupo, inadvertently allow two evil female spirits to go out into the world. The spirits, Munkar (Mary Mara) and Nakir (Rebecca Harrell), travel in a time machine to Seattle at the beginning of the 21st century. The monks must follow them and track down the evildoers, who have become women of the night that kill at random. The monks must convince a police detective that they are not the ones responsible for the murders. The screenplay was penned by horror writer Clive Barker.