The six Toa Mahri (Jaller, Kongu, Hahli, Nuparu, Hewkii and Matoro) are riding in the Toa Terrain Crawler through the Cord that leads to the sunken city of Mahri Nui. When they arrive, the machinery gives them their masks and other equipment. As the hatch opens, they are ready to fulfill their mission of retrieving the legendary Mask of Life, which has been lost under the sea. The Toa are first attacked by various undersea creatures. They open fire, but one of them manages to shove Jaller and Kongu into an undersea chasm. Hahli grabs onto the creature’s tail. Farther away, Nuparu and Hewkii are menaced by Gadunka, a sea creature who had grown huge due to the mask’s powers. The beast is armed with squid launchers and sends the two Toa tumbling into the depths, just before Matoro rams an undersea vessel into its mouth. As Nuparu and Hewkii drift towards the bottom, Matoro continues fighting with Gadunka. Just then, Jaller reports that he has found the mask. As he reaches for it, he is picked up by the hand of Hydraxon the jailer, who mistakes Jaller and his team for escapees from the Pit. Suddenly, Spinax the Energy Hound attacks his master Hydraxon, who lets go of Jaller. Hydraxon wrestles the animal off him, and discovers that Maxilos, who has been possessed by the spirit of Makuta, was responsible for sicking his hound on him. As the two giants clash, Jaller grabs the mask and jumps into the open waters. Matoro, riding a mutated sea beast, takes the mask.