The prehistoric tale of a hunter who goes up against saber-tooth tigers and an alien race intent on clobbering his world...Banished from his tribe after offending the chief, Bru stalks into the saber-tooth haunted hills with only a stone knife and the furs on his back, determined to make amends so he can return before the girl he loves is mated to a hated rival. But Bru's plans are thrown out of kilter when he runs afoul of a visitor from another world. Instructed in sciences beyond his simple ken, the savage hunter makes a deal with the mysterious outsider that will allow Bru to return to his people . . . or will it?