Which movie you were disappointed that they had a good interesting concept at the beginning but they abandoned it halfway through ?

Many times I see a movie with a cool concept but quickly get disappointed when they abandoned it for something generic.

One of these types of movie which I really hoped that they sticked with the concept is taken 2 , I really liked their beginning concept of them reversing the roles with the daughter doing the rescuing this time, but unfortunately they quickly abandoned it so that Liam Neeson can be Liam Neeson.

For what movie you felt such a way?