The following version of the book was used to create this study guide: Harper, Lana. Payback's a Witch. Penguin Random House, New York, NY, 2021. Kindle AZW file.

Emmy Harlow left Thistle Grove behind after a disastrous love affair with Gareth Blackmoore, a member of the town's most important family. Emmy has built a life and career for herself in Chicago. She drives back into Thistle Grove after being away for almost a decade only because she cannot bear to let her father down. It is now Emmy's turn as the Harlow scion to serve as Arbiter of the Gauntlet, a traditional series of challenges that crowns one of the town's four founding families as ruler of the magical side of Thistle Grove. Emmy's plan is to fulfill her obligation as the family scion and return to Chicago at the end of the month-long event.

Emmy encounters Gareth during her first night back. He does not even recognize her. Emmy discovers she is wildly attracted to Talia Avramov who will serve as scion for her House during the Gauntlet. Emmy reconnects with her friend Linden Thorn, whose twin brother Rowan will serve as scion for their House. Emmy discovers that Gareth broke Linden's and Talia's hearts in recent months, and that Linden, Talia, and Rowan are determined to stop Gareth from winning the Gauntlet. She also learns that the Blackmoore family has held power so long that they are prospering while other families are in danger of going bankrupt. Though Emmy is bound by rules of impartiality as Arbiter, she agrees to help.

As the Gauntlet kicks off, Talia and Rowan take the unprecedented step of working together, not caring about which of them wins as long as the Blackmoores do not. At the end of three challenges, the Gauntlet stands at a tie with Rowan, Talia, and Gareth each winning one challenge. Talia and Rowan, in a risky move to ensure Rowan wins the final challenge, open Talia for legions of spirits to possess her. Her family is forced to pool their resources to save Talia. In another unprecedented step, Emmy hands over the Arbiter's robe to her cousin Delilah and steps in as proxy for Talia. She figures out the five clues and wins the challenge. That night, Emmy discusses with her father an experience that put her highly in tune with the town. The experience helped her win, though the Harlow magic is typically considered much weaker than the magic of the other families. At this point, her father reveals that the Harlows hold a secret role in the town. Their ancestor was the first to discover a powerful magic source from the lake, and it is available to other witches only after the Harlows filter it to a manageable level. In doing so, the Harlows have little power left for themselves, making them seem weak. Emmy becomes determined to make the Harlows' true role in the town public knowledge, ending decades of being considered the weakest and least important family. Talia declines to take the victor's wreath, handing it off to Emmy instead.

As the novel comes to an end, Emmy and Talia agree to advance their relationship. Emmy makes arrangements to continue her work as a remote employee, traveling monthly to Chicago. Emmy has an honest conversation with Delilah, and it seems things in Thistle Grove are about to change in many ways.