In the time, before time, a great being, named Mata Nui, created our island. After he do that, he created three elemental being: Makuta, Omaya and Ekimu. They were his sons. Even if Makuta was the first who was created (with 3 seconds) Omaya and Ekimu were loved by their father more than him. He was jealous. So one night, he steal three Masks created by his father: The masks of time, life and creation. He imprisoned his family in the masks and hide them. From then, he rule our island. He is evil.
After he won, six Toa fell from the sky and defeat Makuta’s physical form, but his spirit still exist, and rule the island from the dark… He entered in the mind of an Onu-Matoran and control it. Now, he control the most dangerous Rahi to guard the Masks of Power, because, united, the Mask are the only thing who can defeat him…
Sorry for the beginning… Enjoy!