Creatures the World Forgot is a fascinating study in speechless acting that follows a prehistoric tribe of human beings. The adventure begins when a volcano decimates the Dark Tribe, killing the tribe's leader and many other members of the society. To save the survivors from starvation, newly anointed tribal leader Mak (Brian O'Shaughnessy) must lead his people to fertile land. Mak's tribe prospers, and his wife Noo (Sue Wilson) gives birth to two twin boys, Toomak (Tony Bonner) and Rool (Robert John). As the boys grow older, they begin to compete for their father's attention and legacy. The brothers' rivalry grows fiercer and fiercer while their father Mak is busy defending the Dark Tribe territory against marauders. After a raid on the marauders that wins Toomak his wife Nala (Julie Edge), tensions between the brothers erupt into violent conflict. Will the brothers resolve their differences, or will this 1971 Stone Age drama end in tragedy?