Your objective now is to locate the Army Camp where your allies are held captive. Open your map and head to the nearest red dot due southwest. You should see the enemy camp in the world map.
After entering the facility, start by activating the two switches nearby. Go through the newly-opened door and grab the Resurrection Mist in the corner. Exit the room and enter the other door.
Continue to the right until you reach a corridor. Head down and take the door to the lower-right. Run past the holding cells until you reach a green switch and a Medicine Bottle. Activate the switch and return to the corridor.
Take the lower-left door this time. Grab the ?Herb at the end and activate the green switch.
Return to the corridor and enter the door to the upper-right next. Activate the two red switches there to open the door. Enter that room and grab the Mithril inside.
Backtrack to the corridor and enter the northernmost door to find Millie and the others. After the cutscene, you’ll be back at the Safe House automatically.
Back in the Safe House, Yvena will brief you about how to get to Jie Revorse. After rescuing Millie and the others, make sure to re-equip their gears since they’ll be stripped of it. Don’t worry since the removed items are returned to your inventory; you just need to equip them again.