When he was a boy, Luc's mother would warn him about the mock men living in the trees by their home — chimpanzees whose cries would fill the night. Luc is older now, his mother gone. He lives in a house of mistreated orphans, barely getting by. Then a man calling himself Prof comes to town with a mysterious mission. When Luc tries to rob him, the man isn't mad. Instead, he offers Luc a job. Together, Luc and Prof head into the rough, dangerous jungle in order to study the elusive chimpanzees. There, Luc finally finds a new family — and must act when that family comes under attack.