Well it depends on which game because each Dark Souls game have a different story with little to no connection with the previous. But I'll try to explain.Darkness is coming to devour the entire world and you, as the Chosen Undead, who is incapable of dying, must choose a path to whether you light the bonfire to slow down the inevitable, or let the darkness come.There's so much to talk about the franchise, but I think it's for the best if you experience it through yourself. You'll find a lot of lores through weapons, items, and NPCs while you're playing through the game.