S1·E8 Ghost of Black Lake

This episode begins with David explaining how gnomes make glass. Then he is called to the palace, where the king tells him about a little wizard named Tiraland. The wizard stole all of the gold in the castle, and now the trolls have thrown it into the eerie Black Lake. David has to ask permission to go to Black Lake from the ghost of Black Lake Castle. The ghost is a shape shifter, and agrees to let David go for only three days. David locates the gold with the help of an otter. The trolls have tied a rope around the gold bag and are about to pull it up. The otter removed the rope and ties it to a big rock. The trolls chase David and Swift, thinking they have the gold. Finally the trolls get scared by the ghost and give up the chase.