Return to the Dark Island

(prologue)
The overlord was never truly defeated, once Zane had sacrificed himself, Ninjago was no longer disturbed by the overlord. That is until today. The ninja all have children, who all have powers, who have to deal with the overlord. And they have some things about their powers they do not understand. So with the overlord trying to find them, they need to train harder then their parents ever did.