Hundreds of years ago, we, the Matoran, found ourselves adrift at sea. Searching for a new home, we eventually stumbled upon an island. Despite the dangers, we settled in for the long haul, erecting a wall to keep the island's dangerous Rahi beasts at bay. In time, we created the village of Ora-Koro and began exploring the island. The coast was charted, but the deep forests, treacherous mountains, and boiling volcanoes contained mysteries.
One of the village elders, Turaga Ranga, proposed an idea: an expeditionary force to explore the island and catalogue locations and creatures. His fellow Turaga, Watiri and Nongu, agreed, and asked for volunteers. In the time since the Expeditionary Guild was founded, many species of Rahi have been discovered, and the area around Ora-Koro has been thoroughly mapped. For the time being, Ora-Koro is safe.
However, Turaga Watiri has received a vison: a great evil will come in the future, threatening to enslave the Matoran. Heroes must be created, and the only way to do that is with Toa Stones. Hidden on Avsa Nui are six Toa Stones. These stones, once touched by destined Matoran, transform them into mighty Toa, heroes who wield and control elemental powers as an extension of themselves.
Time is running out, and the Expeditionary Guild has doubled their efforts to find the Toa Stones...