Seven years since the Monsterpocalypse began, Joel Dawson has been living underground in order to survive. But after reconnecting over radio with his high school girlfriend Aimee, Joel decides to venture out to reunite with her, despite all the dangerous monsters that stand in his way.
An adventure-loving couple convince their friends to explore a remote, uncharted cave system in the forests of Northern Australia. With a tropical storm approaching, they abseil into the mouth of the cave, but when the caves start to flood, tensions rise as oxygen levels fall and the friends find themselves trapped. Unknown to them, the storm has also brought in a pack of dangerous and hungry crocodiles.