According to the narrator, courtesy is the most fitting virtue for knights in love with ladies. As Calidore continues his journey, he comes across a young man of about 17 (Tristram) fighting on foot against an armed knight while a lady watches from nearby. To Calidore’s surprise, the young man defeats the knight and kills him.
Fighting without armor, Tristram is at a great disadvantage and much more likely to be injured. Any knight who would attack an unarmored boy would not have been a very honorable knight.
Calidore asks the young man why he’s bloodied his hands by killing a knight. The young man replies that normally he wouldn’t kill a knight, but the knight started attacking him, even though the young man wasn’t wearing armor.
Killing a knight is a serious offense, but it would be justified in self-defense, particularly for a boy without armor.
The young man gives more details, telling how he saw the knight coming through the woods with his lady, and the knight made his lady walk on foot while he rode, using his spear to push her forward when needed. The young man criticized the knight for this, and that’s how the fight began. Calidore praises the young man’s actions.
The dead knight acted very discourteously toward his lady, not only refusing to let her ride on the horse, but even prodding her along as if she were herself a wild animal. Calidore clearly doesn’t approve of this, and so he takes the unarmored young man’s side.
Calidore and the young man go to speak to the lady. She tells how she was traveling with her knight, when all of a sudden, he saw another lady (Priscilla) and got jealous of her knight (Aladine). The evil knight tried to take the new lady but she got away, and so the knight continued on with his current lady, taking out his frustration on her.
Knights like Blandamour and Paridell have shown the dangers of fickleness in knights. The evil knight that the young man describes here should have been satisfied with the lady he already had, but his lust and greed made him try to steal someone else’s lady, then take out his frustration on his own.
Calidore says the young man is clearly noble and asks about his background. The young man reveals his name is Tristram, and he’s the son of a king from Britain called Meliogras who died and left behind a widowed wife, Queen Emiline. The queen fears for Tristram’s life, so she sends him to Faerie Land where he'll hopefully be free of assassination attempts. Rather than resting in Faerie Land, Tristram has been training himself by learning about the forest.
Noble blood in the poem often leads to both virtue and exceptional fighting skills, and Tristram has both these qualities. His virtuous nature means that he isn’t content to just hide and rest while avoiding assassination attempts, so instead he works on improving himself.
Tristram would like to travel with Calidore and learn about knighthood from him, but Calidore says he promised to complete his quest alone. He suggests that instead Tristram help the lady who is now all alone. And so, Tristram takes the armor off the knight he just killed and rides off with the lady.
Calidore is an unusually solitary knight compared to some of the other protagonists in the book. His refusal of Tristram shows his dedication to his own duty.
Calidore rides on until he reaches a place where a knight was severely wounded by the knight that Tristram killed. Next to the injured knight, his lady weeps. The lady tells her story, and it turns out she is the lady that the dead knight was trying to capture. She managed to run away and hide, but it looks like her knight was mortally wounded defending her.
Calidore sees firsthand that Tristram’s story was true. The lady and injured knight have clearly been victims of injustice, and so Calidore knows that the courteous thing to do is to try to help them however he can.
Calidore informs the woman that the knight who wronged her is already dead, which brings her some relief. She doesn’t want to bother Calidore to help with her own grievously wounded knight, but he volunteers to give the injured knight a balm and help carry him to a nearby castle.
Calidore does the courteous, hospitable thing by offering to help a random knight and lady that he met on the road. Helping people in immediate need often takes precedence for a knight over focusing on long-term quests.