Takdain "Dain" Goremite the Powerful and Stubborn male dwarf, Eldirgloeth "Eldir" Olivefold the Practiced Forester male elf, and Axilithaur "Axil" the Scaled Spellweaver female dragonborn take point in the discussion. They agree there was a pull to the North in their visions, past the forest, past the mountains. Winkba Bogden the Lateral Think, a female gnome, offers specifically that there's a sunken castle at the end of the journey. Axil takes the magician's component pouch, to Eldir's disdain. Eldir and Dain have adventured together before. Axil is young and hasn't been involved in much adventuring yet. Winkba tends to be a sneak (in fact, she's already snuck off). The three spend the night.
The three head North through the forest. Eldir finds a handful of what he thinks are spiral mushrooms, good for a sleep-well potion. By midday they make it to the mountains and Tilmindeth. They are hailed by the guards and sign the paperwork to enter. Dain asks around and suggests visiting the Rosey Peachfuzz, the rowdiest elven tavern. They inquire about a lake to the North and learn of lake Goliath, and the legend of infinite tentacles. They learn about fishers that visit the lake, and are given directions to the Office of the Fishing Bureau. There, the receptionist, on their request, schedules some time for them to talk to her supervisor. She gives a little more information about the fishers, but nothing out of the ordinary. Eldir suggests visiting Elderice library, where his friend Elderice can help.
At the library, the receptionist recognizes Eldir and lets him and his companions in. Elderice wheels over on a ladder to see who it is. Eldir asks about legends of tentacles around lake Goliath. Elderice suggests some places to look in the library: the general record, the record of legends, and the record of subaquatic structures (all records are indexed by topic, time, and recorder). They yield a few interesting tidbits: George the human wizard who raised an elven-like home in the area, and disappeared around 400 years ago. Strange fishing-related events seem to occur on a 100-year cycle, with the current era landing on the strange part of a cycle. And a boat found a kilometer from lake Goliath with no explanation, around 200 years ago.
They spend the night at an inn on the North part of Tilmindeth. Axil goes to bed. Eldir makes his sleep-well potion and shares it with Dain, who heads to bed. Eldir stays up a bit. After a little while, his vision narrows. He concentrates on his cup. Slowly, he starts to feel freed of his body, as if his perception happened to be in a body right now, but didn't have to be. He has no desire to explore though; the sensation of exactly now is all he feels or needs to feel. A few hours later he stumbles off to bed. These were not spiral mushrooms.
The next day they exit Tilmindeth. They sign out, Dain giving a different name to mess with the elves. They travel out of the mountains and into a swampland.
A few hours into their trek, ravens start circling. Unsure what it means, they stop. A giant eagle-looking bird swoops into Axil. Sparks burst from the bird's talons as they contact her. Axil is knocked to the ground. The bird lifts off again. Eldir and Dain mount attacks but miss. Dain gets back up and launches a firebolt toward the bird. It hits, but the bird seems to control the fire to mitigate damage. It comes in for another attack on Axil. This time Eldir and Dain's attacks hit. Eldir sinks an arrow down the side of its neck, and Dain smashes it's beak and head, in a spectacular fiery display. The ravens clear. Eldir pockets some of the beak shards and a talon.
They continue north. Eldir finds some witherweed and harvests it. Eventually they come to a black lake, that they determine must be lake Goliath. They find an abandoned dock and settle for the night.
In the morning, the three head East, where they can't see the shore, and find a boathouse in working order. They wait. Three elven women show up to go fishing. Dain convinces them that they filed the correct paperwork to be taken on a tour. Each of them get into a boat with an elf. The fish they catch are mostly sunfish, and some eels. They stay near the shore, where the fish are.
After the fishing session, the elves head to an outpost to process the batch of fish. Eldir sits down to make some witherweed arrows. Dain and Axil explore further east along the shore.
Dain sees it first: what must be the infinite tentacles. A dark mass of reticulated arms reaching out of the lake and pulling trees in. They are so dark they appear flat. The trees are slowly, surely, and meticulously pulled into the lake; no debris are left behind. Dain approaches and shoots a crossbow bolt in; no response. Axil shoots a firebolt, which simply passes through. Unsure what to do, they head back. The tentacles retreat back into the lake before they get back.
Eldir and two of the elves are skeptical of the story. The last elf looks and sees the missing trees. They all head over. Everyone believes the story, but the leftover evidence isn't convincing; it looks like there never were trees. The elves head back to make a report. The three continue following the shore.
At the Northwest section of the shore, they make camp for the night. While Eldir is on watch, an arrow whizzes past his head. He wakes the others. Dain quickly alerts and finds something to smash: a goblin. After flattening a cylindrical volume of one of them, he establishes they are carrying bows and are indeed the aggressors. Dain catches one with an arrow. Some others wail and flee.
The one that caught the arrow was unlucky enough to survive. Dain presses on its wound, asking where it's from. It gobbles and makes universal obscene gestures. He tries again, and this time the goblin blurts: Glorbdak. To the North. It blacks out. Dain and Eldir throw it into the lake. Dain starts walking off, but the goblin has woken again from being put in water and starts swimming to shore, so they wait for it. It drowns.
In the morning, the three complete their circumnavigation of the lake.
They get into two boats (Eldir on his own) and head to the center of the lake. All sound is dampened there. Axil puts her head in the water and the effect is amplified. It's also impossible to see any distance; all black. While making observations, Eldir sees black tentacles creep up the side of his boat. He signals the other boat to come closer and jumps aboard. After paddling away, the other board is pulled down. They paddle back.
They concoct a plan to get to the bottom of the lake. Eldir modifies a boat so it can be turned upside-down and walked down into the lake. They do so, Axil in the front, the tallest, Dain in the middle, dangling and keeping the board down, and Eldir in the back. When the air starts getting thin, they collide with a rock. They follow its edge, which eventually becomes very flat, under the algae. Interested but running out of air, they turn back.