Launcelot rides around randomly until it gets dark. As the daylight fades he finds a crossroads which features a rock he can’t see on account of it’s dark, and also a chapel. He figures this is as good a place as any to stay overnight, so he ties up his horse and hangs his shield up. Then he goes to the chapel door to knock, but it turns out the chapel is disused and half-ruined. Inside, though, there’s your classic strange adventure inexplicably well-tended altar, with cloth of clean silk and a fair clean candlestick of silver. Launcelot wants to go into the chapel and pray, but he can’t find a way in; the main entrance has collapsed.
“Well dang it,” grumbles Launcelot. He goes back to his horse and sets up to just sleep overnight under the stars.
As he lies there dozing, he witnesses a thing that happens! A couple of shining white horses trot of up the road, supporting a litter between them. On the litter lies a sick knight, who mopes aloud about how long he’s been on the Grail hunt, and how he hasn’t seen the Grail even though he’s been looking for it, and complaining to God about how unfair that is, and so on and so on.
Then the candlestick from inside the chapel comes floating up out of nowhere, levitating without support. Also there came a table of silver and the holy vessel of the Sangreal. Launcelot recognizes the Grail when he sees it, because (Malory reminds us, in case we forgot) he saw it back in Book XII, Chapter 4.
The sick knight sits up in his litter, and plucks the Grail from the air. “Thank you God! Also I would like to be healed of my malady please.”
Then, boom, he’s miraculously cured of his wholly undefined malady! “Thanks again, God!”
Launcelot tries to jump up and nab the Grail, after that. He’s still lying by the side of the road half-asleep, remember. But because he’s not perfect, he fails to catch the Grail as it exits and instead he just lies there in a stupor.
Meanwhile the formerly-sick knight climbs out of his litter.
“Congratulations! How’re you feeling?” asks his squire, who Malory assumed we knew was there all the time. The squire may or may not be Jesus. I’m going to go with he is Jesus.
“Pretty okay, I think. Got rid of my malady, so that’s good. What do you think about that knight over there, the one lying by the side of the road half-asleep and pretending to be completely asleep?”
“Looks like he’s got some sins on his conscience, and that’s why he didn’t leap up and embrace the Grail when he had the chance,” says Jesus. Jesus is an astute student of the human condition.
“Poor guy,” says the knight. “I mean, obviously he’s a knight of the Round Table, which means he’s on the Grail Quest, and look at how close he came just now! I feel bad for him.”
“Enh,” says Jesus. “Here, take his helmet and his sword and his horse.”
“Isn’t that stealing?”
“Not if you have My permission! I’m Jesus, remember?”
So Jesus and the mystery knight ride off, with some of Launcelot’s stuff.