The Haunting of Cassie Palmer is a story of 13-year-old Cassie Palmer who lives with her mother, older brother, and sister. Cassie's mother is an eccentric "psychic" (medium). After some of her clients are incensed to discover her mother has tricked a woman into thinking that she is communicating with her deceased husband by brushing her face with a feather, the clients threaten to prosecute her. Mrs. Palmer pleads with them not to as such an action would render her homeless.
Mrs. Palmer explains to Cassie that her powers are only intermittent, and as result she sometimes has to embellish the reading to produce results her clients will be happy with. Mrs. Palmer explains that Cassie, being seventh child of a seventh child, would develop great psychic powers as she reached maturity. However, Cassie has no wish to be a psychic. Unfortunately, these abilities have already manifested and Cassie is simply unaware of them.
Desperate to protect her mother from charges of fraud, Cassie goes to a cemetery to try to call up a spirit Charlotte Webb who died as a small child. Instead a dark figure appears from behind a tombstone. He tells her his name is Deverill and wants to know why she's summoned him. Cassie runs away.
Cassie eventually tells her mother who soon is gravely concerned for their safety. Deverill appears to Cassie several more times, but aside from Cassie and her mother, no one can see or hear him. Unsure of Deverill's intent, she invites him to her house so that her mother can find out what his motives are. He complies but vanishes before her mother can discern if he is a sinister or benevolent entity.
Eventually the Palmers have to sell their house and move to another town as a result of poor business and the bad reputation acquired from the clients who accused Mrs. Palmer of fraud. Deverill reveals to Cassie that when he was alive he buried a small treasure in the floorboards of a house in town. Cassie finds the treasure and is able to use it to purchase a new home for herself, and her mother and two older siblings to start a new life. In exchange for this good deed, Mr. Deverill is able to leave this plane of existence for the great beyond. Cassie had freed his restless spirit of an eternity of darkness and torment. Her psychic powers apparently were burned out during the struggle thus enabling her to lead a normal life, free from the influence of the supernatural.