Cassie and Sam prepare for the next chapter of their lives as Nick and Grace get ready to graduate and attend college. On the last few days of school, Grace helps a local fashion designer make a dress for a client. Martha continues to try and find clues to the Middleton treasure, and Nick’s mom, Linda arrives in town. Stephanie and Adam struggle to balance their workload and their relationship.
While working with the fashion designer, Mrs. Hansen, Grace discovers she loves fashion and creating pieces. George stops by to help Mrs. Hansen move some items and she offers him an old safe, but warns him she has no idea how to open it. Elsewhere, Donovan says “I love you” to Abigail but she is unable to say it back to him. She looks to Cassie for advice on expressing her true feelings to Donovan. A little while later Donovan opens up to Cassie about his declaration and she encourages him to give it time. Cassie, Sam, Nick and Grace share a special dinner together at the bistro on the eve of Graduation.
Grace tries on Mrs. Hansen’s completed dress when Cassie shows up and surprises her by telling her the dress is for her own graduation. Vincent returns home to attend the ceremony. George works on the safe and is able to get it opened on the 13th try. Inside, Sam finds another clue to the Middleton Treasure. Vincent talks to Stephanie about selling her portion of the food truck to a popular blogger. It seems like a great fit and they both are ecstatic. Sam and Linda surprise Nick with a computer system perfect for any gamer.
Sam and Martha discover a new clue from the fireplace located in the Mayor’s office. Later, Sam and Cassie head to the tunnels under the town to find the next clue to the Middleton treasure. There, they discover a keyhole and use the key Martha previously found to open it. The two discover a music box, which they give to Martha.
Cassie says goodbye to Nick as he leaves to spend the summer with his mother before going off to school. Abigail tries to say “I love you” once again to Donovan but still has trouble getting the words out, making her wonder if this has anything to do with the curse. When Martha listens to the music box, a trap door opens revealing a jewel. Cassie surprises Grace with a vintage sewing machine and the two spend time together as mother and daughter.
Three months later, Cassie returns home after dropping Grace off at school. Sam and Cassie are thrilled to start their new chapter post-children at home with each other.