Plot summary [1]
Upon his arrival in the Stone Age, Mark ventures out of the space-time machine in search of food and water. He is soon accosted by a group of Neanderthals who drag him back to their cave lair. Mark suspects he is to become dinner, so he shoots one of his guards and escapes, barely managing to evade his captors in an all-night chase. Mark finally finds a place to hide and collapses into exhausted slumber.
When he awakens, Mark sees a reindeer-like animal, and takes two more shots from his revolver to take it down. After building a fire and roasting part of his kill, Mark again feels he is being watched. Rather than more Neanderthals, however, he sees a human figure resembling an American Indian whom he suspects is a Cro-Magnon man. He offers to share his food, and they establish a rapport, both realizing neither intends to harm the other. Mark discovers the man's name is Tlaxcan. In the face of an imminent storm, they cooperate to build a crude lean-to and rest for the night.
When Mark wakes up, Tlaxcan is nowhere to be found, but he notices a group of vultures circling not too far away. Mark investigates to find Tlaxcan lying injured near a dead wolf-like animal. Mark tends to Tlaxcan's wounds and they set off to return to Tlaxcan's home.
They reach the valley of the Danequa, Tlaxcan's people, only to be confronted by several Danequa men. Tlaxcan vouches for Mark, but tensions are still high. Qualxan, the shaman of the tribe, takes Mark alone into a cave and puts on a ritual display of "magic" in order to establish his dominance over Mark. Mark leaves the cave and uses his matches to "create" fire out of thin air in front of the whole tribe. This earns him the respect of many members of the tribe, but an old warrior, Nranquar, is unimpressed. He maintains the only way for Mark to prove himself is to join the hunt for mammoth.
When the time for the hunt comes, the whole tribe participates. Their strategy revolves around distracting and agitating the mammoth herd enough that they can induce it to stampede off the edge of a cliff. At one point during the hunt Nranquar is about to be trampled but is rescued by Mark, who is himself injured.
At the conclusion of the hunt the tribe celebrates with a massive feast at the site of the mammoth stampede. After the revelries Mark and Tlaxcan leave with the bulk of the tribe, returning to their valley taking as much of the meat as they can carry, leaving a small contingent of hunters to guard the remainder of the kill.
When Mark and Tlaxcan return to the site of the kill to relieve the guards, they spot circling vultures and suspect an ambush. They change course and manage to avoid the Neanderthal trap, but the Neanderthals, in frustration, charge wildly after the two. This results in a furious chase across the plains, eventually landing Mark and Tlaxcan in a deep cavern where they battle a bear-like creature. Finally prevailing against these threats, they return to the valley of the Danequa.
When the tribe learns of what has happened they hold a war council and decide to embark upon a campaign against the Neanderthal settlement. During the time when the Danequa are preparing for war, Qualxan hints that he knows Mark will soon be leaving the Danequa and returning to the "land of his fathers". Qualxen suggests that before he leaves, Mark visit Tloron, a Danequa holy man.
Tlaxcan leads Mark deep into a cave in the valley where he finds Tloron working by the light of soapstone lamps on a magnificent cave painting. Mark realizes that he has seen this particular image before, 50,000 years in the future, yet he is witnessing it at the moment of its creation.
Finally the Danequa march off to war. A battle ensues, and Mark and Tlaxcan pursue some Neanderthals across the plains in the direction of the space-time machine. The two friends prevail against the Neanderthals, and Mark says his goodbyes. He sets his return time to 15 minutes after he left his own time, and returns home.
