Sludge
After rescuing the prince we began to cast about for what to do next. We discovered that the prince saw suspicious activity to the southwest of town. Circumscribing the town, we set off to the check it out.
A few miles to the southwest we settled down and I read the waves. Nothing was really out of place, save the siren's presence in the city. Not too useful there. We changed tactics and began to spiral out in a search pattern looking for things out of place.
First, we picked up a faint trace in the water. Oily, sludgy, unpleasant. Clearly this was wrong. It was diffuse, so we couldn't pin down where it was coming from. We set out to find the source, and eventually traced it to a cave.
Cade went first with me right behind. I was in the form of an octopus before the befouled water made me sick and forced a change back. Surely this was the right place. We descended deeper and deeper, before long passing below even the sea floor itself. There was no life in these caves, and the area was strangely clean. Then…
It spoke to us in our heads. It tried to bargain, but this sort of thing can only be dealt with in one way. It spoke of a mole in Phlan, though it may have been merely playing on our doubts as it clearly could read our minds. In the end, it had to be dealt with. It tried to play some tricks on us, but we closed. Logru took quite a beating, but we were able to keep him alive. Eventually the beast dropped and we had a festival with the merfolk and sea-elves to celebrate.
Upon returning to town, we collected our reward and planned for our next adventure.