When Christian leaves Vanity Fair following Faithful’s death, he is joined by Hopeful, who tells him that soon even more men from the town might join the journey to the Celestial City.

They are met by Mr. By-ends from the town of Fair Speech. Mr. By-ends is traveling the road to the Celestial City, but he tells Christian and Hopeful that he is interested in religion only if the way is easy. The two men leave him as a bad influence.

Mr. By-ends continues on his way and meets with Mr. Hold-the-World, Mr. Money-love, and Mr. Save-all, all of whom he has known since they were in school together. All of them agree that it is no sin to use religion to gain a higher standing (and more money) in the world. They catch up with Christian and Hopeful and pose the question to them, but they refuse to have anything to do with the group.

Leaving the four men, Christian and Hopeful travel through the Valley of Ease, which is very narrow, and arrive at the hill of Lucre, where there is a Silver-Mine that has been the downfall of many. A man called Demas urges them to come and look into the pit. Hopeful suggests that it would not be hurtful, but Christian says that they must not be tempted. They go on, and soon Mr. By-ends and his friends come along and are lured into the pit.

Soon Christian and Hopeful come to a monument in the shape of a woman. They see that it is Lot’s Wife, who was turned into a pillar of salt for looking back at the burning city of Sodom. On the road they come to a river with a pleasant meadow and fruit trees on both sides. Here they take some rest and refreshment.

Journeying on the next day, they come to a Wayside, which Christian suggests will be an easier path to the Celestial City. Hopeful is concerned about leaving the path, but he is persuaded by Christian.

It is not long before the two travelers realize their mistake. Christian apologizes for leading Hopeful astray, and they turn back toward the path. Not reaching it before nighttime, they lie down to sleep and are awakened by Giant Despair, whose lands they are in.

The giant takes them to his home called Doubting Castle. He imprisons them and deprives them of food and water for four days. Despair’s wife, Diffidence, urges him to beat them.

After much suffering and thoughts of suicide (at Despair’s suggestion), Christian remembers that he has a key called Promise, which opens any door in Despair's castle. The two men manage to escape with the aid of Christian’s key and return to the true path. They erect a sign of warning at the stile leading to the Wayside.