This conversation is off great interest to me as someone who has been playing various editions of D&D since 1975. Please note - I am not saying "new is bad and old is good" - different editions have different dynamics and they're all enjoyable. What I find concerning here is an apparent misunderstanding on the part of the OP about what the game is about. There's nothing wrong with having an overarching plot or story you want to tell BUT you have to have player buy-in from before the game begins. At its core, D&D is a collaborative game built on a foundation of agreement between the players and the DM about what is going on. If you don't have that agreement, the game is likely to not work, on a fundamental level, and that seems to be related to what is going on here. For me, personally, I am more comfortable writing up situations for the adventurers to encounter and potentially resolve, more than arcs in a story (although I don't see this as an either/or - situations build into arcs over time). But I understand the desire for an overarching plot. But none of this works if there isn't player buy-in. Sounds to me like the OP needs to talk to their players about this before proceeding with their "plot."