I cannot access the "Fire in the Gloom" quest?

[Niwashi]

There's a couple more quests in between Gridanian Envoy and Fire In the Gloom. The order for your next few quests is:

The Gridanian Envoy
Call of the Sea
It's Probably Pirates (includes Sastasha Seagrot dungeon)
Call of the Forest
Fire in the Gloom (includes The Tam-Tara Deepcroft dungeon)
Call of the Desert
Into a Copper Hell (includes Copperbell Mines dungeon)
The Scions of the Seventh Dawn

It sounds like Call of the Sea is the next one you need to pick up. Get it from Bartholomew in Uldah's Royal Promenade (upper level area of Steps of Thal). If you've finished The Gridanian Envoy, you should have airship travel unlocked for easy access to any of the three starting cities. You'll be expected to travel back and forth between all of them from here on out.