Simplify the following text for a Grade 8 native English-speaking person.
Original: Zelda asks Link to smuggle her out of the castle so she can investigate the Tower of Spirits , where she believes something has happened to cause the disappearance of the Spirit Tracks .
Simplified: Zelda asks Link to bring her out of the castle so she can see the Tower of Spirits , where she thinks something has happened to make the Spirit Tracks fade away .