two colonists die in a reptile attack that night, and the next morning a man named norton arrives at the settlement, claiming that he is from another colony that was wiped out by the reptiles. while the doctor is investigating the dome of the dead colonists he is surprised by a mining robot controlled by caldwell, a mineralogist for the imc (interplanetary mining corporation). caldwell invites the doctor to talk to his bosses and hear their side of the story. his superior, dent, is a ruthless mining engineer, who has been using the mining robot to scare and now kill the colonists – something which caldwell finds repellent. dent knows the planet is rich in rare minerals and wants it for imc and his greedy troops agree that this should be done at any cost.