At the new frame church built at the corner of four counties in western Kansas, a strangely sinister Episcopal bishop comes to town to conduct a confirmation ceremony. Twins Lottie and Josie Albright, who are attending the ceremony to watch the confirmation of their niece, are agitated by the bishop's scathing sermon. And their pastor, Reverend Mary Farnsworth, has fled to the anteroom after dropping the chalice during communion. Josie, being a psychologist, lingers after the service in hopes of comforting Reverend Mary, but Lottie immediately orders her sister to leave when they discover Reverend Mary's dead body. Lottie, left alone with Bishop Talesbury, is frightened by the bishop's strange rituals for disposing of the spilled wine, but as deputy sheriff, she is duty bound to attend to the death.
Back at the county-wide picnic, an elderly lady tells Lottie that a man kneeling next to Reverend Mary during the service had scared her into a heart attack. Worried this was not a natural death, Lottie calls in other law-enforcement agencies. She soon learns that their beloved Reverend Mary was a woman without a past and that the rogue bishop has unexpected ties to western Kansas. A sheriff from an adjacent county, unaware that Josie is an FBI consultant, assumes that seizing control of the investigation will be easy and instead arouses the wrath of the twins. Although they are used to double trouble, nothing has prepared them for the malevolence that is stirred up by the death, by some old documents that Lottie uncovers, and by the reemergence of some murderous, century-old rivalries.
