Following the defeat of the Skull Grinder, the Toa and Ekimu are at work rebuilding the City of the Mask Makers, which the inhabitants of Okoto are moving into. After learning from the new arrival Melea that her two young nephews, Ako and Oda, have been kidnapped, Ekimu and the Toa set out to rescue them, unaware that Makuta has sent a Skull Spider to free Kulta and give the villain a chance to redeem himself. The Toa follow the trail of the abducted villagers into a mountain range, where Lewa is attacked and abducted by a large hawk under the control of a Skull Spider. After it takes him into one of the mountains, the hawk attacks the other Toa but is freed before departing; it is later seen by Kulta as he follows them.
Ekimu and the other Toa soon discover that Lewa and the captured villagers are in the hands of the Skull Raiders, an ancient band of pirates of whom Kulta is the leader. Worse, they learn that the Raiders are also in league with Makuta, prompting Gali to challenge their commander Axato to a duel. As the pair fight, the other Toa and Ekimu break free of their cells and proceed to rescue Lewa and the two youngsters, only for Kulta to arrive. A battle quickly ensues, until Ekimu challenges Kulta to single combat and promises that the Toa will not join the fight and that he will not use the Hammer of Power he previously wielded to defeat Kulta.
The two foes then clash, but Ekimu reveals an intentional loophole in his agreement to face Kulta by asking to borrow Onua's hammer, which he uses to knock Kulta into the ceiling of the underground city, causing it to collapse. The Toa, Ekimu, and the villagers escape, and Ekimu and Onua use their hammers to collapse the escape tunnel, trapping the villains forever. They then return to the city, while Kulta pleads to Makuta for help but goes unanswered.