You've learned that the Collective built a hideout deep within one of the cave networks in Draullir.
Go through the door deep inside the cave in the mission The Baryte Rush. The conversation with Lynx starts the mission.
Speak to CruxEdit
She is the leader of the base and has a problem with someone who is faking the Charlatan's orders - giving bad intel. It has already gotten two recruits killed. She asks Ryder for help to subtly find out the guilty party. It's one of the people in the base. When the conversation is over, the mission completes and the follow-up mission The Charlatan's Charlatan starts.