so.. what's the twist? (spoilers)

Everyone in the reviews is talking about a supposedly twist, but I didn't see any twist. Pretty soon into the movie you figure out they are a cult waiting for the eclipse. So they do their stuff at the end. They disappear and the girl gets accused. I don't see a twist... or did I miss anything? It was fairly obvious the guy was not who he was saying to be, and something like that was going to happen at the end. Of course I don't really get why they disappeared but I guess we're just supposed to accept it in the context of the movie with the ritual and all that. I don't see how it's a twist.

I sorta enjoyed the movie but I feel like there should be more to it. It just ended and that's it. A little disappointing.