After reuniting with Sabin on Mt. Kolts/Mt. Koltz, you continue to the Returners' Hideout.
Find the Hideout
After leaving Mt. Kolts/Mt. Koltz, go north in the overworld and enter the first cave. Talk to the guard. After the guard escorts you, go through the door next to the guard and talk to Banon.
After the cut scene, when Terra awakens, have her talk to Locke. Open the chest, then leave the room. Go north across the bridge and enter the room to the north. Open the chests and check the bucket and pot in the upper part of this room. Exit the room, then go southeast and talk to Sabin. Go up and check the pot beside the suit of armor. Then go north into Banon's room and talk to Edgar. Open the chest in the corner, then leave Banon's room. Go west and talk to the guy guarding the hideout entrance.
Go outside and talk to Banon, then say No when prompted, and you will automatically go back in. Keep going out and telling him no. Eventually there will be an automatic scene. (Alternatively, you can just say yes, but you will miss out on an item.)
During the cut scene, if Terra said no three times, you get the Genji Glove. Try equipping it on Terra.
After the cut scene, you will be in control of Edgar. Before you continue, press X to go to the options menu, press left, and select Banon twice to put him in the back row. Then go north to return to Banon's room, then use the leftmost exit of Banon's room. Go south to the inn, and rest. Save at the save point in Banon's room, then go south to use the secret exit from Banon's room, and keep going south to go to the Lete River/Lethe River. Check on the raft to jump onto it.