According to the Flat Kingdom's founding legend, the world was once chaotic because the three-dimensional realm dominated everything. A wise sorcerer created six Magical Jewels to hold the third dimension at bay, and peace followed. Then the masked thief Hex stole one of the Jewels and kidnapped the princess, breaking the balance and allowing chaos to return. The only being who can withstand the 3D chaos is Flat — a small shapeshifting hero whose ability to change form is also his only method of fighting. He sets out to stop Hex before the kingdom collapses entirely.