Breaking Quarantine Trophy in Aliens vs. Predator
Escape from the Research Lab
How to unlock Breaking Quarantine
This is story related and cannot be missed.
Straight after the previous trophy (Come To Mama) you will enter a room with two androids and another control panel as your objective. Kill the androids and press square once again to interact with your objective. Another cut-scene will play that shows the labs big double doors opening allowing the matriarch to escape with a lot more aliens. You will get the trophy during or after the cutscene.