With Halloween fast approaching, Cassie and the town of Middleton are hard at work preparing for the annual Harvest Festival. This year, Cassie is transforming Grey House into a delightful haunted house, and when a handsome stranger checks in, the family suddenly find themselves on edge.

The author of a series of magic-and-romance-filled novels comes to Grey House to celebrate the release of her newest book, titled "The Enchantress Unites." But it's Cassie who ends up doing the uniting, bringing together the people of Middleton to put on the special event while also coming to a special realization about Sam.

A long-forgotten prophecy is unearthed and when the things that were predicted to happen start to come true, the people of Middleton begin to fear this might be the sign of a horrible curse.

Cassie and Sam puts their energy into the bicentennial Halloween Harvest Festival. Everyone in town prepares for the festival’s competition with rival town Blairsville. When a 100-carat ruby known as The Heart of Middleton is stolen from the museum where the festival’s gala is to be held, Cassie suspects a Grey House guest is the culprit.

The Good Witch meets her match when Cassie's long-lost college roommate, Autumn Delaney, makes an unexpected visit to Grey House on a mission to disrupt Middleton's Halloween festivities.