I found a secret entrance in the Kitchen castle defense, on the way to the towers when you start pushing them back, you can see a zombie-like figure peek out from behind third rock. (it's a bit darker) You'll find a sewer and meet Nitramj. It's pretty creepy, he is half-zombie since they distributed the antidote a bit too late. Anyway, he'll challenge you to his trial. Should you accept, he takes all your weapons, but he'll give them later if you beat it.
It's basically just a revamped zombie escape. Also, a car chase from Mogarf the Mighty.
Then he'll give you Akimbo spears.