The book is a continuation - with a completely independent plot - of the famous story of the same author "The Struggle for Fire." The book describes the adventure journey of two prehistoric people of the Stone Age - the young men Una and Zur, who went to scout new hunting sites for their tribe. On the way, they engage in battle with a saber-toothed tiger mahayrod and with a giant python; meet with the Forest People, with whom they make friends, and save them from the warlike and bloodthirsty tribe of the Fire People. And finally, they tame a giant cave lion, which, in turn, repeatedly comes to their aid.