Instant Eels are a species of animals from The Magic Tree Of Nowhere. Courage tries to protect the tree from Eustace (who wanted to cut the tree down). Courage uses the bulldozer the tree gave him to dig a moat with a small island surrounding the tree, and makes a massive sandcastle fortress to protect it. Courage takes a bag that says "Instant Eel" and he pours it out of the bag and into the water. A massive green gulper Eel emerges and roars at courage, before pausing to sing.
Eustace charges, but Courage throws marbles at him and Eustace slips and falls into the water and the Instant Eel bites Eustace and Eustace jumps out of the water screaming. Eustace ties a hankerchief around a huge boulder and swings it high which causes Eustace to fly until he will reach the island. Courage uses a huge baseball bat, but Courage knows that Eustace is gonna miss. Eustace crashes into the wall of the sand castle and falls into the moat again and the Eel attacks Eustace again.
A lot of battles weren't shown. Eustace gets on a catapult and cuts the rope and says "Chop chop chop chop!," but he falls into Courage's boiling stew and falls back into the moat. Both Eustace and the eel then rise out of the water and start singing together for a brief moment until the eel grabs Eustace and shakes the farmer in his jaws.
- The song the Eel sings is a ballad called Danny Boy, a message from a parent to a child who is leaving for war.