It was all her! I think.
And we never find out WHY! Though we can guess.
A religious group buys an island and cuts themselves off from the rest of the world.
Then divides up the island because they think their leader has broken a rule and gone nutty after his wife dies.
Or maybe nuttier. Couple of opportunistic whack jobs from the get go.
It felt a bit choppy and disjointed, but a nice slow burn to the end.