Original: They begin their journey together to stop Darken Rahl and prevent him from opening the boxes of Orden : magical devices which can give absolute power over life and death . Kahlan tells them that Rahl has two of the boxes but requires the third before he is able to make the magic work .
Simplified: Zedd then decided that they need to cross the boundary to stop Darken Rahl from conquer the world using the magic of the boxes of Orden .