Wait for Dennis' call then proceed to Citra's Temple, as marked in the map. Stand in the entrance to meet up with Dennis then follow him to meet up with Citra herself.
After downing the stuff, watch for scene then follow the man. This is pretty much straighforward so just keep moving forth until you find and reach an ancient dagger. Leave the temple afterward to complete the mission.
This mission will give you fast-travel access to Badtown and unlock 26 new skills.