The time: 1934. The place: Moradamee, Michigan's most haunted county. Vyvyan Stroker has come here to be with her spouse, Professor Abe Stroker, who's spending his sabbatical leave in this cursed backwater to research the Dark Lover of the Swamp ("not one but many"), who leads maidens to their destruction by promising them their heart's desire.
Vyvyan and Abe's marriage and mettle are tested by their time in Mordamee, where they encounter a series of supernatural incidents and a host of local characters, all tied up in one way or another to the Dark Lover or the swamp-or both.
* Spader Sodcleft, town drunk and gravedigger, who knows where all the bodies are buried-literally and figuratively.
* Roly Hogworm, village idiot-who reminds Vyvyan, cryptically, that the Dark Lover has a sister.
* The Reverend Fyron Brimmeston, a hellfire preacher with an unhealthy fixation on the painting hanging in the Strokers' rented cottage.
* Doc Birney, country physician, who befriends the family and, being an outsider himself (having lived in Mordamee for only 40 years), is perhaps the most normal person in town (except for his anthropomorphic fetishizing of his automobile, Ol' Betsy).
* The Widow Wycherly, a crotchety herbalist suspicious of the townsfolk (and vice versa)-not to mention outsiders like Vyvyan. She nonetheless ministers to the Strokers when they're overcome (via supernatural agency) by the "green misery."
* Auda, Mrs. Wycherly's granddaughter, a sweet, naïve young woman who's hired by Abe as his housekeeper, befriended by Vyvyan, and pregnant by (she says) a handsome stranger who lay with her last spring and has promised to return in a year for her and the baby.
* Lon Norder, Mordamee's stalwart sheriff, who saves the family from an impossible beast and develops an immediate rapport with Vyvyan-which blossoms into a full-fledged affair (which doesn't end well).
* Violet Crabtree, Mordamee's vibrant, vivacious schoolteacher, a self-possessed young woman who manages to charm everyone she meets, from the men (with whom she flirts) to the young women like Auda (whom she impresses with her manner and style)-everyone, that is, except Vyvyan, who tries to like Miss Crabtree but finds her somehow perverse.
Strange and perverse incidents inform their year in Mordamee, culminating, one spring night when temperatures are topsy-turvy (cold by day, hot at night), with the disappearance of Auda's baby, the long-awaited appearance of the Dark Lover, awful revelations and confrontations, and a superhuman struggle between unadulterated evil and the fallible forces of good.