Sea Slug

Making Swamp Paste
Swamp paste is created by adding a pot of flour to swamp tar, and cooking the raw swamp paste over a fire. Swamp tar is scattered on the ground in the swamp south of Lumbridge Castle. If you don't already have one, you can get a tinderbox from the Lumbridge General Store as a free sample. You can also get regular logs from the third floor of the Lumbridge Castle. Thus, swamp paste can be made with almost no effort, and at no cost.

The Fishing Platform
Talk to Caroline in Witchaven, east of East Ardougne, who will tell you her husband, Kent, and son, Kennith, are missing. She will ask you to go to the Fishing Platform to find them. Holgart has a boat that he can maybe take you in.

Talk to Holgart, and he will tell you his ship is in need of repairs. He will ask you to go and get him one swamp paste to fix it up. Once you give him the swamp paste, Holgart will appear in a cut scene fixing the boat. Talk to him again to go to the Fishing Platform.

Investigate
When you arrive you will notice the odd behaviour of "everyone", as they all seem to be in a zombie-like trance.

Look around and find Bailey inside a small room on the platform to the west and talk to him. He will tell you about the odd happenings and the hauling up of the sea slugs. Also, pick up the broken glass in the northeast corner of the room for later in the quest.

Helping Kennith
Go to the ladder in the north west corner of the platform, and pick up some of the damp sticks near the ladder. Climb the ladder once you are ready, and look around if you wish. In a room on the west side, past the crane, you will find Kennith. After talking to him he is too horrified to leave with all the sea slugs and the strange fishermen. He will tell you to find his father, Kent, and to hurry and help him.

Go back to Holgart and talk to him where you arrived there. He will take you to a deserted island, where you will find Kent all alone. Talk to him, and hear his story about the sea slugs and how he really is trying to help Kennith then ask Holgart to take you back to the platform. Try to climb up the ladder. The Platform fishermen, possessed by the sea slugs, will stop you. Talk to Bailey to find out the slugs weakness. He will give you an unlit torch as they are afraid of Heat.

Use the broken glass on the damp sticks to make dry sticks, then rub them together to light the torch. Climb up the ladder again, and talk to Kennith. From outside the room, kick the badly-repaired wall (east facing, north end) to make an opening. Talk to Kennith again first, kick the old crumbling wall beside him, then talk to him again, and rotate the crane to save him, shown in a cut scene. Talk to Holgart again to return to shore. Finally, talk to Caroline to finish the quest.

Reward

 * 1 quest point
 * 7175 Fishing experience
 * Access to the Fishing Platform
 * Oyster pearls

Music
Music tracks unlocked:
 * Fruits de Mer
 * The Mollusc Menace

Trivia

 * When using a unlit torch on a Sea Slug or a Fisherman, it made a glitch as if fire was being stretched.
 * When you are on the island with Kent, Kennith's ball is a reference to Wilson the volleyball in the movie Cast Away.
 * This quest bears many similarities to the movie the faculty, which was based on an earlier book.
 * The music track unlocked during this quest, is called Fruits de Mer, which is french for Seafood.