Thaddeus is a mysterious, stout traveling showman who arrives in town wearing a white suit and red vest. With unusual eyes and a persuasive pitch, he sells small white cards with red spots for fifty cents, promising they can grant any single wish. He travels constantly, leaving his customers to deal with the exact wording of their desires without his interference.

Polly is an eleven-year-old girl living in Coven Tree who struggles with a sharp tongue. She frequently speaks her mind without considering how her blunt honesty might hurt others, which leaves her socially isolated. Desperate to be liked by the popular, wealthy girls in town, she hopes to use her wish card to gain social acceptance.

Rowena is a romantic fifteen-year-old who creates grand fantasies about her future. She is deeply infatuated with a traveling salesman who visits her family's farm, captivated by his stories of worldly travels. She hopes to use her magical card to make him stay in Coven Tree permanently, ignoring the steady presence of the people already around her.

Adam is a sixteen-year-old boy who works on his family's farm, which is notoriously the driest in the county. He spends his days exhausted by the endless chore of hauling water from Spider Crick. Frustrated by the daily hardship and the drought, he looks to Thaddeus Blinn's magic card for a quick solution to his family's water shortage.

Stewart is the pragmatic owner of the Coven Tree General Store and the narrator of the town's strange events. As a central figure in the village, he hears all the local gossip and observes the residents carefully. Though highly skeptical of magic, he buys a wish card out of curiosity and keeps it safely stored in his cash register.

Sam is a seventeen-year-old farmhand employed by the Jervis family. Tall, practical, and plainspoken, he provides a grounded presence on the farm. He is highly observant and quickly sees through the shallow charm of visitors, offering steady and dependable support to Rowena despite her initial dismissiveness.

Henry is a traveling salesman for the Neverfail Farm Implement Company. He uses smooth flattery and impressive stories of big cities to win over his clients and their families. He presents himself as a sophisticated worldly traveler, capturing Rowena's romantic imagination while primarily focusing on making his next sale.

Leland and Lenora Wickstaff are siblings who live near the woods and possess a deep knowledge of local plants and animals. Though they are shy around most villagers, they offer genuine and loyal friendship to Polly, contrasting with the superficial popular crowd she tries to impress.

Agatha is a wealthy and popular girl in Coven Tree who takes pride in her social standing. She places high value on appearances, proper manners, and wearing frilly dresses. She frequently acts with snobbery toward those she considers beneath her, particularly targeting Polly with public ridicule.

Eunice is a popular girl in Coven Tree who closely aligns herself with Agatha. She shares her friend's concern with social status and polite appearances while actively participating in the exclusion and mocking of other children in the village.

Uncle Poot is a local dowser hired by farmers to locate underground water sources. He practices the traditional folk method of using a forked branch to divine water, treating his ability as a rare, inherent gift rather than a simple trick.

Mr. Fiske is Adam's father and a hardworking farmer struggling to maintain his land during a severe drought. He possesses a stubborn pride that prevents him from asking his neighbors for help, forcing his family to endure exhausting daily labor to secure water.

Mrs. Jervis is Rowena's practical mother. She recognizes the realities of farm life and manages the household, remaining appropriately skeptical of traveling salesmen who try to charm their way into free room and board.

Sven Hensen is the local blacksmith in Coven Tree, known as the strongest man in the village. He represents the physical strength of the community and is quick to offer his muscle when his neighbors face unexpected crises.

Olivia is a classmate of Polly's in Coven Tree. She represents the general student body who is accustomed to Polly's blunt remarks and reacts with surprise when treated with unexpected courtesy.