Lizard

In the future, convicted Teens have a choice. Life in prison, or taking their chance in The Caves. Two Teens are dropped onto a remote island, along with a cyborg monster. If they kill the cyborg, they go free. If they fail, they die. Zak, the wild boy of the island, watches the Teens. Sometimes he helps them. Sometimes he doesn't. There are six The Caves titles: Dogs, Lizard, Drone, Spider, Lion, Snake. They can be read in any order.