After Sir Bagdemagus fails, Galahad wins a miraculous white shield marked with a red cross. The white knight who defends the shield tells Galahad its history — it comes from the days of Joseph of Aramathy and has healing powers — then the white knight vanishes. Galahad's squire, who has heard all this, asks that he may follow wherever Galahad goes. When Galahad hints that he must ride alone, the squire asks to be knighted. Galahad grants it.
Now Galahad is directed to a churchyard where a ghost howls, weakening men and driving them mad. Galahad lifts the lid of the haunted coffin, drives out a fiend, and orders the body removed from holy ground. A good man explains the allegory in the event: the body signifies the foulness of the world, corrupt with the hatred of fathers and sons — one of the reasons Christ was born of a Virgin.
Galahad and his former squire, now Sir Melias, ride together until the road forks. A magic sign says that the left fork can lead to proof of prowess, the right to proof of knightly bearing and personal virtue as well. Melias takes the left. He finds a crown on a throne in a meadow and takes it with him. A knight comes against him and nearly kills him. Galahad arrives to beat the knight and also a second knight, then takes Melias back to an abbey, where he is eventually healed. Galahad learns that in taking the left fork — the road to prowess — Melias acted with pride; in taking the crown he acted with covetousness. The two knights Galahad overcame signify Galahad's triumph over these two sins. No man with such sins in him can achieve the Grail Quest.
Soon after, while Galahad is praying in a chapel, a voice sends him to break the cruel customs of the Maidens' Castle, and he goes. For seven years the castle has been held by seven brothers who murder knights and constrain maidens. Galahad drives the brothers off (he never kills except when God wishes), and Sir Gawain, Sir Gareth, and Sir Ywain slay them. The castle, it turns out, signifies the good souls imprisoned before the Incarnation; the seven knights are the deadly sins; and Galahad is a figure of Christ. Galahad was right, Gawain learns, to let the seven flee. He and his companions are wrong in needlessly murdering. Gawain accepts this but refuses any penance, believing the pains he suffers in battle are penance enough.
Galahad, meanwhile, encounters Launcelot and Percival, who do not know him because he is disguised. He unhorses them both, and when a hermit reveals his identity he rides away from them and out of sight. Launcelot, leaving Percival to seek adventures on his own, comes to a mysterious chapel and soon falls asleep on his shield at the gate. Half-sleeping, half-waking, he sees a sick knight healed by the Grail. Launcelot tries to come fully awake but cannot stir.
The healed knight takes Launcelot's horse, helmet, and sword, and after he is gone a voice tells Launcelot he is harder than stone, more bitter than wood, and more naked than the leaf of the fig tree. He walks to a hermitage and learns what all this means. He has won renown for love of Guinevere, not for love of God; he has fought for right and wrong with equal spirit and all for personal glory or love. The time has come when he must recognize God's kingship whether he likes it or not. Launcelot laments his sins and prays that he may become a better man.