There are a few reasonable expectations the moviegoing public has when they plop down in front of the screen.
1) They're in for at least 80 minutes of something, whether that something be good, bad, or downright ugly.
2) The trailers and promotion materials are somewhat representative of the finished product.
And 3) The top-billed stars will appear in the bulk of the film, for better or worse.
Sometimes, however, filmmakers and marketers work together to blow up those last two expectations.
Because even though your favorite movie star's face might cover 50% of the movie poster, are the most heavily featured actor in the trailer, and diligently make the late night talk show rounds to promote the film, that doesn't necessarily guarantee they'll make it to the end of the movie.
Hell, sometimes they don't even make it out of the first act. Sweeping the rub out from underneath the audience like that isn't always a successful move, but more often than not it at least ups the stakes and keeps viewers on the edge of their seats.
SPOILERS AHEAD OBVIOUSLY...