Crusoe is astonished one day to discover the single print of a man’s naked foot in the sand. Crusoe is terrified and retreats to his “castle,” where he entertains thoughts that the devil has visited the island. His conclusion that it is not the devil’s but a real man’s footprint is equally terrifying, and Crusoe meditates on the irony of being starved for human contact and then frightened of a man. Driven wild by fear, Crusoe fortifies his home and raises guns around it, keeping watch whenever possible. Concerned about his goats, he contrives to dig an underground cave in which to herd them every night and creates another smaller pasture far away to keep a second flock. Crusoe spends two years living in fear.
Coming down to a far part of the shore, Crusoe finds the beach spread with the carnage of humans. Eventually realizing that he is in no danger of being found by the cannibals, Crusoe’s thoughts turn to killing them as perpetrators of wicked deeds and thereby saving their intended victims. Waiting every day on a hillside fully armed, Crusoe eventually changes his mind, thinking that he has no divine authority to judge humans or to kill. He also realizes that killing them might entail a full-scale invasion by the other savages.
Crusoe describes the measures he takes to avoid being spotted by the cannibals. He rarely burns fires, removes all traces of his activities when leaving a place, and even devises a way to cook underground. While descending into a large cave he has discovered, he is shocked to see eyes staring at him. Crusoe is frightened and returns with a firebrand, only to find it is an old he-goat. Crusoe is pleased with this new cave and considers moving into it. Mounting to his lookout spot later, Crusoe spots nine naked savages on the beach, lingering among the remains of their cannibal feast. He proceeds toward them with his gun, but when he arrives they are already out to sea again. Crusoe inspects the human carnage with disgust.
On May 16, Crusoe is reading the Bible when he is surprised by a distant gunshot followed closely by another. He senses the shots are coming from a ship and builds a fire to notify the seamen of his presence. By daylight he perceives that the shots have come from the wreck of a ship whose men are now either gone or dead. Once again he thanks Providence for his own survival. Going down to the shore, where he discovers a drowned boy, he prepares to paddle out to the ship in his canoe. He finds the ship is Spanish and contains wine, clothing, and a great treasure in gold bars and doubloons, all of which he hauls back to his dwelling.
Crusoe reflects on the “original sin” of disobeying his father, recounting the foolish decisions he has made throughout his life. One night he dreams that eleven cannibals arrive on his island to kill a victim who escapes and runs to Crusoe for protection. About a year and a half afterward, Crusoe finds five canoes on the island and thirty cannibals on the beach preparing two victims for slaughter. After the first is killed, the second breaks away and runs toward Crusoe’s hiding place. He is pursued by two cannibals but is faster than they are. Crusoe attacks both pursuers and persuades the frightened victim to approach. Finding Crusoe friendly, the native vows devotion to his liberator. After burying the remains of the two pursuers so as not to be tracked later, Crusoe and the native return to his camp, where the native sleeps.
Crusoe names the native Friday to commemorate the day on which Crusoe saves the native’s life. Friday again asserts his subservience to Crusoe. Crusoe teaches him simple English words and clothes him. Returning together to the slaughter scene, Crusoe has Friday clean up the bones and skulls and tries to convey to his servant the horror of cannibalism. Crusoe is delighted with his new companion and teaches him to eat goat meat instead of human flesh. He realizes he must expand his grain cultivation, which Friday helps him to do.