City of Ember

This is a really good adventure movie for the kids. I'm a pretty choosey parent when it comes to movies, and all of mine watched it.

Ember is a fully-contained city built underground to house a human community for 200 years as a shelter from an unspecified disaster. A box has been provided which automatically opens after 200 years, and contains a plastic card and instructions for returning to the surface. Mayors of Ember keep the box a secret and only disclose its existence to their successors in office. When one mayor suddenly dies while still in office, the box is passed on to the mayor's family, and is left in a closet in their house. It is thus unnoticed by anyone when it automatically opens as designed. Read on here...