Amelia and Professor Adam, finishing up a day at the North Dakota dig, discover a strange cave with a light glimmering inside. A weird Anomaly floats in midair within the cave, and when Amelia touches one of the outlying sparks of light orbiting the central mass of the Anomaly, it flashes brightly and disappears.
Once their vision returns, Amelia and Professor Adam leave the cave, and realize things are different. Professor Adam sees a lizard and tries to puzzle out its species, while Amelia circles the hill and sees a lake where none was before, with Bison and Zebras taking water, neither of whom should be co-existing in the same wild environment. When she brings the Professor to see, they both witness a Water Predator of prehistoric proportions snatch a zebra underwater.
Professor Adam begins teaching Amelia the basics of survival, while trying to figure out how to get back from where they have found themselves. Amelia, on the other hand, begins befriending the strange lizard they found the first time they exited the cave into the new world. They build a fire near the mouth of the cave where they first entered this world, and sleep in the entrance tunnel.
The next day, they do what they can to observe the local ecosystem from the relative safety of the hill. They observe Saber-toothed Cats on the hunt, and a pack of Deinonychus stealing about half of the Cats’ kill, as well as some smaller species. And they observed a roughly conical robot arriving at the lake. When it was attacked by a particularly aggressive Deinonychus, it demonstrated the ability to generate a deadly energy blast, but did nothing else.
Another night passes. As the Professor and Amelia continue to figure out ways to survive in the Anomaly world, they discover the robot has taken up a position on top of the hill that houses the cave, but makes no other moves.