Detention Island is an island that used to be a top-secret military prison and now is used by Experimental Punishment System for kids who get detention.
The kids are led through the island by the Disciplinarian, a hologram, to an air pad on top of the mountain. In order to redeem themselves, each kid has to solve a problem based on his or her skills and what he or she got detention for in the first place. For example, Bucky has to answer geology questions because he skipped science class to watch a daylight meteor shower (it ended up being a flock of geese).
However, if the Disciplinarian discovers that there's cheating going on, like bringing the Ninja with them (although unintentionally on their parts), he makes the challenges even harder and calls it Death-tention Island. Instead of Morgan having a little dance-off with the Disciplinarian, she has to dance for her life. The more difficult challenges are still possible to defeat, though, like Bash succeeding by shooting Bucky through a fiery ring. The Disciplinarian becomes very aggressive after the Ninja interferes with the challenges for Bucky and Morgan, and gets worse as the cheaters continue through the island with success. Finally, he uses his robot form to attack Howard for his challenge, but the Ninja steps in and destroys him.
McFreaksMcFist captured four of them for his McFreaks show. However, Randy breaks them out, and soon Randy returns them to Detention Island in "McFreaks".
Barnabutt is a brown creature with the face of a mandrill, two legs, and four colorful butts surrounding his head. He is able to shoot a sonic pulse from his butts.
Rondo is a mix between a brown bear head (with the top of the head being bald) and a purple octopus body with the tentacles.
The nine-arm snake is a blue-green snake with nine arms and orange-brown hair on his head. He It is quite capable with machinery, hotwiring and driving Slimovitz's Car, as well as piloting (but not being able to land) McFist's hovercraft.
The toucan shark is a mix between a red parrot head and a shark body. He is still able to fly, he has parrot legs, and he has sharp teeth in his beak. He is able to spit acid.