Valmont is transformed into a 10 yr. old kid by Daolon Wong after he angers the dark chi wizard during an encounter. Meanwhile, Jade who is feeling down about being small begins to mess around with magic to help her become a little taller. It backfires as Jade begins to grow at a dangerously rapid rate. Besides attempting to reacquire the power of the horse talisman before Daolon Wong gets it; Jackie, Uncle, and Tohru must now also deal with Jade's abnormal growth spurt and a rambunctious little Valmont.

While attempting to stop the Enforcers from getting the fourth oni mask, it accidentally lands on Captain Black's face. He uses the powers of the mask to help him easily take down the Enforcers. Jackie and the rest of the group become worried when Captain Black becomes very intrigued and excited by his newfound abilities.

Captain Black's true good side is able to ward off the influence of the mask for a while, but the dark power of the oni begins to slowly corrupt and take hold of him. When the darker oni Captain Black finally emerges, he attempts to take advantage of his full access to Section 13. Jackie, Jade, Uncle, and Tohru race to work on a way to keep the other three stored masks away from Black as they search for the ingredient needed to perform a removal spell.

After many failed attempts to acquire the power of an oni mask, Hak-Foo finally gets one. He is a disappointed in the small size of his shark like shadowkahn, but Hak-Foo soon discovers their monstrous appetite for devouring shadows.

Jackie, Uncle, Tohru, and Jade discover that they have overlook something in the ancient writings by making the horrible mistake of placing the final oni mask along side the other eight in Section 13. By doing this, they have released Tarakudo and his generals from the masks that bind them. The entire world begins to be engulfed in total darkness as the shadokahn are now free to walk the earth.