Personally, I'm not too big a fan of "twist" endings, because it involves the author lying to his reader--this is self-defeating because the author needs the trust of said reader for proper suspension of disbelief. Even if this is just the introduction of the story, I think the tone of the story would be better served if you put the last paragraph at the beginning and get it out of the way, or make it a lot more clear that Engie is an Unreliable Narrator before you tell us "oh, by the way, what is actually going on is [X]".