Monty's mother, Camenbert Kate, arrives for a visit, and it's none too pleasant for the Aussie Ranger. No one pushes Monterey Jack around except his mother, and she pushes at the wrong time -- just when the Rangers are trying to stop Fat Cat form pulling his biggest crime yet. Fat Cat, determined to rid the city of dogs and humans, is using an army of moles to undermine buildings. It's mass evacuation as the entire city begins to look like it's filled with Leaning Towers of Pisa. Monty has to prove to his mother he's a man, err mouse, in his attempt to stop Fat Cat.