Having answered the group's questions, Bahamut calls in a low voice. A lithe human woman emerges and nods to the party.
"Rachaela will guide you to the appropriate doorway in Sigil. Follow her. Once you reach the appointed place, provide the astral diamonds in the pouch she is providing you to the person inside and say where you want to go. He may require some persuasion to allow you to pass, but you are more than up to the task. I look forward to speaking again in the near future; I will be watching."
And, in the blink of an eye, Bahamut is gone. Rachaela hands the pouch to Zog.
"You hold this. Follow me."
She leads the group through the streets of Sigil. The first thing you notice is that this city is the most bizarrely diverse place you may have ever been. No two buildings are the same--indeed, the styles of buildings, even the material lining the streets, varies widely from building to building. Sturdy dwarven homes lined with stone walkways fall into the obsidian road which then turns to gravel in front of graceful wooden spires constructed by eladrin along wooden walkways. You have clearly emerged in the Guildhall Ward and start circling around a sloping path through that ward, with commerce being conducted on every side in front of a dizzying array of buildings. You regularly pass people haggling in front of them over use of their portal keys.
The portals themselves, as it soon becomes clear, are not just doors or gates. They can be spaces in the wall, gaps in the air, passels of clouds, or so on. As you pass out of the Market Ward, you walk through the bustling Guildhall WArd and through orderly and quiet Clerk's Ward, and yet do not stop there.
You can talk among yourselves and earn Bennies by roleplaying in the following thread:
link to a message in this game
It is not until the vestiges of civilization begin to break down that you stop. You are right on the edge of the darkest ward of Sigil--a slope looking down at a ramshackle packet of buildings known throughout the multiverse as the Hive. Rachaela stops and smiles a wry smile.
"I will not make you go in there, friends, though I suspect individuals of your background might find it...interesting. No, follow me into there."
She points to a dark doorway to the right, where she enters. The room beyond is half-filled with mist. A wizened man looks up at the group, clearly surprised.
"Here, now," the old one says.
"You are too bright and true a group to be here. Go away."
Feel free to make skill checks to figure out this area and to back up your roleplaying of interaction with this old fellow. Use skills you are good at--success or failure matters.