While celebrating Friendship Day, the pups spring into action to prevent Mayor Humdinger from ruining Adventure Bay's reputation as the friendliest town on the map. Humdinger waylays Mr. Postman, forcing the pups to take over the delivery of Friendship Cards. He also sabotages Chase's truck to prevent him transporting Mayor Goodway's Friendship Cake. When one of Humdinger's plans accidentally sends a fleet of rabbits airborne on little balloons, Chase, Skye, Zuma, and Rocky must use all their skills to mount a rescue. Meanwhile, Marshall and Rubble confront the inhabitants of a spooky old house who have nabbed a bag of Friendship Cards. With Ryder's help, the pups deliver both Cards and Cake, save the balloon bunnies, and even make a couple new friends: all in time for the big Friendship Day celebration.