Star Trek / The Original Series / Windows on a Lost World / V. E. Mitchell

While Kirk, Spock, Chekov and an archaeological team are exploring the ruins of an ancient civilization on the uninhabited planet Careta IV, they discover strange devices that appear to be simple windows. But the windows prove dangerous when Kirk and Chekov enter them, and disappear. Now, while the two struggle to survive, Spock struggles to unravel the mystery–while fighting off aliens.