Who put the cat among the pigeons? Unfortunately we are unable to get hold of a copy of the book. Please can anyone help.

Question

put/set the cat among the pigeons (British & Australian)
to do or say something that causes trouble and makes a lot of people angry or worried. "Tell them all they've got to work on Saturday. That should set the cat among the pigeons. "

This is an idiom... You did not say what book you found this in.