Now that Staelwyrn has ample evidence against Sevrin, he asks for your assistance.
This quest is only available if you started the game in Limsa Lominsa, and you have completed the quest Plowshares to Swords.
Starting the Quest
Talk to Staelwyrn at Summerford Farms in Middle La Noscea to start the quest. There will be a cutscene.
Speak with Grynewyda
Go up to the top of the hill and talk to Grynewyda next to the shed.
Leave Summerford Farms and go north across the bridge, then follow the path northwest. Go down the wooden stairs and talk to Aylmer.
Rescue Sevrin's Henchmen
Go northeast down the wooden stairs to reach Woad Whisper Canyon. You'll find Eyrimhus. Check on him.
Go northeast again and you will find Sozai Rarzai. There will be a glow around him, indicating another instanced battle. Check on him and there will be a cutscene, and then the battle will ensue.
Solo Duty: Just Deserts
In this battle, a mysterious black-robed figure will summon a Clay Golem. During the battle, the golem will use the attacks True Grit and Plaincracker. True Grit is a cone attack, and Plaincracker is a circle attack centered on the boss. To avoid these attacks, step out of the orange area before the enemy's cast bar is full.
After the battle, there will be a cutscene. This one is important, so you should probably not skip it.
Speak with Staelwyrn
Afterward, go back up the wooden stairs and make your way back to Summerford Farms. Talk to Staelwyrn and there will be a cutscene. Talk to Staelwyrn again afterward.
Speak with Baderon
Return to Limsa Lominsa and talk to Baderon in the Drowning Wench, which is near The Aftcastle aetheryte. There will be a cutscene. Afterward, inn rooms and levequests will be unlocked.
Large cities have inns that you can enter for free by talking to an innkeeper. They are marked on the map with a bed symbol. In the inn room, you have access to a Summoning Bell, Crystal Bell, Toy Chest, Glamour Dresser, Armoire, The Unending Journey, a bed, and an Orchestrion.
Some of these features are unavailable for now, but you can use The Unending Journey to re-watch cutscenes, and you can use the bed to /doze on (i.e. use the Doze emote on) or use it to log out or exit the game. (You can also log out or exit the game anywhere via System in the Main Menu.)
Levequests provide a way to earn experience, gil, and miscellaneous rewards. Talk to T'mokkri in The Drowning Wench to unlock them. From then on, you can talk to her to see the list of available levequests.
The Recommendations window is also unlocked. You can open it via the main menu, in Duty > Recommendations. You can select "All" to see all recommended activities in your current area, or select a specific item from the drop-down menu. For example, in an overworld area, you can select FATEs to see which FATEs are active in your area that are equal or lower than your current level. The Recommendations window can be helpful if you are not sure what to do next.
Next Main Scenario Quest
After completing the quest, you will need to be at least level 10 to proceed to the next quest. At level 10, if you have completed your level 10 job quest for your current job (available in your job's guild), you can unlock other combat classes by talking to the Guild Receptionists in the various guilds in Ul'dah, Limsa Lominsa, and Gridania. After you reach level 10, talk to Baderon to accept the next quest: Sky-high.