If others are in favor of a different story, I might have one . . .
"In the far future of Spherus Magna, Matoran and Agori live in peace and work to better themselves and their civilization. The Toa of the time are not evolved Matoran, but are actually created in factories. Though only one Toa is currently protecting the most heavily populated area of Spherus Magna, he is one day killed by an unknown being. Leaving behind six ancient Toa stones, six Matoran unknowingly activate tOa Factory and somehow become Toa, like in the days of old. Using their new elemental and Kanohi powers, these completely inexperienced Toa will have to protect the Matoran and Agori of Spherus Magna, investigate the death of the previous toa, defeat the strange criminals that have begun attacking villagers, and even face the threat of a possibly revived Makuta."
Yeah, it's basically Darker And Edgier 2004. But I like it . . .
(And if we want more story depth, we could throw in some racism between Matoran and Agori, showing their world already tearing at the seams.)