The middle of your story should include the problem and solution. If your character is an apprentice, now is the time to make them a warrior. If they're pregnant, have the kits. If they're deputy, become the leader.

We should have our climax. If there's a sickness, now is the time that cats start dying. If there's a natural disaster, now is the time for it to happen. This should be what you've been building up to in your beginning and prologue.

Not much else I can say about this. Does.. anyone have anything to add?