Under the Enemy - Exploring (Act 4, Chapter 4)

All the squad does in Under the Enemy - Exploring, is find the route to the Castle. When they reach the boarder of the outskirts into the main city, they start hearing broadcasts of the Demon Leader. He keeps broadcasting information about the acid facility. He wants the demons to stop experimenting with acid from the outer core of the hive for it could lead to another conflict with the Infectors!