The sewer tunnels of the Cult of the Spiny Rat God

The Heroes of the RedWater Fellowship have some options since the Skaven - rat like humanoids - scurried down a hole. The door the party went through leads to a small passage where the hole goes down through the next deck and into what appears to be a cavern below. 3 doors are also visible, one on right, left and facing you.

The door to the left is smashed open and hangs off 1 hinge. A dark cabin - looking to have a hammock inside. The door to the left is slightly ajar. The door facing them is closed and looks to have a lock as well.

The hole down is dark but you can hear faint skittering noises from the far distance below. 

Below 1 deck they hear muffled thumping and as if a gagged person. exploration reveals a human whom is gagged and bound. 

The man emaciated, tired and very injured man sees Gothie and drops to his knees. It seems he was one of a race of mankind that served Gothie's race, the Foreclaimers. It seems Asagorn the Grim,  was mugged with a group of others whom all had been taken away for sacrifice (?) or other nefarious reasons... 

For saving him, Asagorn swears fealty to Gothie as she of course saved him (not the whole party!).

The party moves onward and then down the hole the Skaven had retreated down. After securing a rope, the party is able to climb down into a cave with a sandy floor, with glowing green moss or mold is covers some of the room. Gothie scavenges some of the glowing moss (tiny glowing flowers) for later research.

The party once again sees the ongoing mural that is either on the floor or walls of the four elvish brothers on a quest. One seemed to have died fighting a multi-headed scaly beast. 
The rogue Kantif using his expert level rogue skills is able to find some traps on the route following the Skaven. There looks to be arcane spells that blasted a door open. Graxusas is able to determine it was a lighting bolt. 
The fetid and putrid smells of the sewer seem to be growing.
Multiple doors and passages are explored, the Gothie's ranger skills come in handy to track 1 of the Skaven. There is a small grate with a narrow 2' wide tunnel it seems to have shuffled around and then moved on again. The party then moves on, and looks into a large

room. A large cistern of swirling sewage seems to enter here. There is a scaffold as well as crane that a group of Skaven seem to be operating. They lift what looks like a humanoid body floating down into the area. Carrying it out it gets drooped into a large group of giant rats which tear into the dead body with gusto. There looks to be one larger Skaven that is directing and yelling at the rest of the humanoid rats.
The RedWater Fellowship prepares an ambush..
Battle!
The whole party focuses fire on the leader and does an extreme amount of damage to the large Skaven, it roars in pain as arrows, bullet and blasts of magic and eldritch energy hit it.
The battle goes back and forth, at one point a sneaky Skaven tosses a large bottle into the midst of the bunched up party which incapacitates 1/2 the party. Cedric uses his Shadow bow to teleport over to where the injured leaders was being healed by a another of the ratmen. The battle at one point did not look good but then all the party used their skills and abilities to tactical effect - Kantif used his sneak attack to great to devastating hits. Gothi's arrows hit and with his ranger skills are deadly. Doc Holliday blasts from his pistol are on target and do massive amounts of damage. Jawbone chews a number of the giants rats, his chewing can be heard rending the flesh as they screech in pain. Hargahoc, the rogue dragonborn assists with his magical enhanced melee attacks. Graxusas' blasts of hit quite often to good effect as well.

One Skaven is able to retreat down into a sewer pipe.. other than that all are defeated. The RedWater Fellowship take stock and rest, gathering treasure and loot. Magical items are identified and chosen by the party as they rest..