Two spaceship crewmembers rebel against the leader, a naturalist named Laird Cunningham, while on a distant planet, and plan to leave him stranded. As he is fleeing the ship to hide in a nearby cave, he damages the ship enough to keep the crew grounded. Cunningham spends the first night in cave, and as a new day starts, he discovers and studies plant-eating, crablike beings. His two ex-assistants exit the ship in heavy utility suits to start the repairs with welding tools. Cunningham ponders whether the protruding knobs could be the crablike beings’ eyes. A larger species attacks one, killing and eating it. Then, a huge centipede appears and scavenges the remains. Cunningham explores the cave and finds an exoskeleton of the crablike creature. He examines the knobs, still wondering if they are eyes, but cannot convince himself they smell or hear due to lack of atmosphere. Another killing takes place and the centipede emerges soon after, killing and eating both creatures. The centipede disrupts a herd of the crablike beings, who rush into the cave. Cunningham kills a few to study them. He discovers metallic liquid in their body cavities, which attracts the centipede. With this, he realizes the knobs are used to smell. The centipede was smelling the metallic blood. During the night, he kills a few plant-eaters, pouring their blood into grooves in the sand so they cool and solidify into rods. He places the rods into the damaged spaceship. The next day starts and the ex-assistants resume their work. Quickly, six of the centipedes show up and swarm the men, creating a distraction. Cunningham rushes to the ship. He humanely leaves the outer door open so that his assistants can escape and calls for rescuers from another planet with the transmitter. Cunningham tells the ex-assistants to stay in the airlock until the rescue ship is here.