Accepting that it would be best to take the guard captain's deal, you all made your way north through the west wing of Briarstone, seeking the doppelgangers Captain York spoke of. Taking the methodical approach, you went door by door. Through the first door you found the boiler room which seemed inactive and the boilers not running. Under the boiler you saw glowing eyes staring back at you and a pair of dire rats leaped out and attacked you followed by the thing with the glowing eyes which was an odd amalgamation of a monkey and a rat with a face full of small tentacles. You managed to kill them all. Connor took some time to dissect the odd creature and study it. You also found an ongoing light spell under the boiler, which Connor concluded had been cast by the strange rat/monkey thing.
Once Connor was finished with his studies, you ventured further down the hallway and through the next door you found storage rooms which appeared to have been pretty well looted. You took the time to inspect the area and determined that at the very least it didn't seem like this was an abandoned asylum. It had seen somewhat recent use. And in the northern storage room you found that part of the ceiling and wall had collapsed into rubble and a couple giant centipedes had been hiding out in the rocks. Rather than fight them, you fled the room and barred the door.
Continuing on up the hallway you then came to a large open area that appeared to have once been a nurse's station or something similar, the ceiling collapse here was more complete, and entirely blocked off the way north. Amid the rubble you found an old woman who claimed to have broken her leg during the collapse and requested your help. You all were very skeptical of her claims and eventually deduced that she was in fact a doppelganger. After slaying her you continued on into the rubble where you found a half-buried corpse whose hands and head seemed to still be moving independent of each other. Leaving that alone, you went through the last open door you could find and found three individuals shackled to pipes along the wall. One of them was already dead and was being gnawed upon by the second which Josiah identified as a ghoul. The third was cowering against the far wall away from the ghoul.
From the ghoul you managed to determine that he used to be a patient. He doesn't know why or how he became a ghoul and didn't seem too concerned about it. The third man was dressed in an odd makeshift robe that seemed to be made from sheets dyed a dirty yellow. You deduced that he was likely one of the patients as well as he didn't seem capable of saying more than a few different phrases. You killed the ghoul and continued on into the laundry room where you found a couple large tables separated by a sheet hung up across the room. One was piled with bodies. Upon investigation you were attacked by a crazed old woman who you very quickly put down, but who did not seem to be a doppelganger. Another middle aged woman claiming to be a Doctor you found on the other side of the sheets. She said she was attacked by the shapeshifters and brought here and asked for your help. You brought her back to the guards, but when she introduced herself, the guards looked confused. Eventually after one went to speak to their "leader" and returned he said that the Doctor she claimed to be had been found dead yesterday. The "doctor" fled down the hallway and a chase ensued. After a hard fight where half the party nearly died, you eventually cut down the doppelganger and dragged your unconscious friends back to the guards.