Search and Destroy

This quest becomes available if you’re still allies to the Brotherhood and upon discovering Acadia in the island. Take note that doing this quest, you’ll lose access to the quests tied to the NPCs in this location. If you still want to push through with this quest, make sure to complete all other Acadian quests first.

Travel back to the Prydwen and talk to Kells. You can then convince him to send an attack force to take out the synths in Acadia. Once done, travel to the staging point south of Rayburn Point. Talk to Knight-Captain Larsen, the leader of this assault squad then tell give him a go when you’re ready to attack.

In Acadia, the refugees and the named characters (including Kasumi) will fight back. Take them all out then once cleared, talk to Larsen to complete the mission.