Surrounding the Plaza of Remembrance in Jarlsburge is Jubilee Park. Four bridges connect the Park to the Plaza, the Bridge of Dawn, the Bridge of Day, the Bridge of Dusk, and the Bridge of Night.
At the southern base of the Bridge of Night is a Hellmaw, a gateway to the Nine Hells. This particular gateway connects to Nessus, the ninth layer of Hell, specifically within close proximity to Malsheem, Asmodeus' citadel.
Very few in Jarlsburg even know it exists and those who do are uncertain of how long it has been there. Some wonder if perhaps Scylla Stonepillar's betrayal involved more than the drow of Xi'Nuln, and involved an infernal agent whispering in her ear, twisting her mind and destroying her soul.
Recently the Brotherhood of Bones and Teeth, abyssal terrorists in service to Pale Night, discovered the Hellmaw and manipulated the late Stanis Krauss into obtaining the Alabaster Bouquet, a magic item that can open any door. The Brotherhood were planningto infiltrate Nessus and attempt to assassinate Asmodeus himself.
Thankfully the Brotherhood was stopped and the Bouquet seemingly destroyed do to the quick actions of a ragtag band of Ironcloaks in the Watch. They were aided in their battle by Karol Sonar, Jarlsburg's Minister of the East.
Sonar, Adder Vitriol, Hight Inquisitor Lot, and Prime Minster Belladonna Malifaux believe they are the only citizens privy to the locations secret. What Sonar and Malifaux are most disturbed by is that they believe the Hellmaw may open from the other side.