Annika, Mystal and Ape change back into their adventuring gear and, for the rest of the night, whilst Cormondal parties, explore the underground cistern thoroughly.
The cistern has twelve pipes that lead to it, six from the north along the banks of the Leng, and six from the east along the banks of the Anhoi. These all start along the ghats of the riverfront, and are covered in gratings that have not been moved for years. The slope down to the cistern; the idea being that floodwaters from the rivers first flow into the cistern to absorb sudden changes in river level.
Of these twelve tunnels, three have been broken through at various places; these you have already explored - two lead into the cellars of the abandoned houses in town and one to the garden of the Magister. The two abandoned houses show no sign that anyone has been through them since you last checked.
There is an inspection access that leads to the Old Barracks in the east of town but, as before, there are old rusty gates hedl shut with an old rusty chain.
It looks like the two known surviving members of the paper lantern gang have not used any of these exits. They both jumped into the water to escape and, being undead, could have survived underwater indefinitely. Either they are still there, or there is an underwater exit.