Mario and his friends are invited to the Flower Kingdom by its ruler, Prince Florian, to witness the power of a Wonder Flower. Bowser crashes the ceremony, steals the Wonder Flower, and uses its reality-warping magic to fuse himself with the kingdom's castle, transforming into a sentient flying fortress. He imprisons the kingdom's citizens, the Poplins, and begins plotting to enslave the entire universe. Mario and the group set out alongside Prince Florian to gather six Royal Seeds scattered across the kingdom's regions, each one removing a layer of Bowser's defenses and bringing them closer to a final confrontation.