King Mark sneaks out of his own castle like a criminal, because he doesn’t want anybody to see him ride off into the woods to ambush and murder Kay. He brings along only his most trusted men, including Sir Andred (see, I told you he’d be okay) and definitely not including Sir Dinas. They dress up all in black, and ride out to the woods by the back way.
Mark’s plan, as Gaheris predicted and Kay foresaw, is just to ambush Kay and murder him before he knows what happened. However this plan gets foiled inasmuch as Kay is way better at spotting ambushes than Mark is at setting them.
“Ho, strange knights all in black whom I certainly don’t recognize as a certain asshole king and his asshole nephew,” calls Kay. “I see you there, in the bushes! Come on out and let’s have a nice friendly eyes-open joust, what do you say?”
Mark reluctantly engages Kay in a joust. Even so, he cheats! He rams Kay’s horse with his own, much larger horse. Kay’s horse falls down, with Kay underneath it. Kay gets bruised full sore and lies there, trapped under his horse.
“Knight, sit thou fast in the saddle, for I will revenge my fellow!” shouts Gaheris, and charges Mark for another joust.
Gaheris terrifies Mark, Malory tells us, but Mark jousts him nevertheless. Of course Gaheris effortlessly dehorses him, and Andred too for good measure. Then, while they lie there reeling, Gaheris gets off his horse and helps Kay get out from under his.
The two Camelot knights approach the two Cornish knights. “Don’t kill us!” wails Sir Andred, crying like a little baby. “It’s King Mark and only Sir Andred! He’s a king! I’m just a knight! I was just following orders! Please don’t kill me!”
“You would-be ambushing dicks,” says Gaheris. “Why shouldn’t we kill you?”
“I’m a king! I’m a king!” cries Mark. “Anointed with oil, Biblical tradition, divine right to rule, legit king, over here. Also I can pay you! I have a king’s ransom at my disposal!”
“Feh,” says Gaheris to Mark. “I wasn’t even talking to you. I was asking why we should spare Andred. You, we’re definitely going to kill. Sparing you was never on the table. Thou art a king anointed with cream, and therefore thou shouldst hold with all men of worship, and therefore thou art worthy to die.”
“Ooh, nice burn,” says Kay.
“I know, right? I’ve been saving that one,” replies Gaheris.
Gaheris raises up his sword to slice Mark’s head off, and Mark drops to his knees and sobs and begs and cringes and promises that never while he lived would he be against errant-knights. And also he sware to be good friend unto Sir Tristram if ever he came to Cornwall.
“Fine, you big baby,” says Gaheris. “You know you really take all the fun out of it.”
Meanwhile Kay is about to go after Andred, but Gaheris stops him. “Wherefore the stopping of me?” Kay asks. “It were pity that he should live any longer, for this is nigh cousin unto Sir Tristram, and ever he hath been a traitor unto him, and by him he was exiled out of Cornwall, and therefore I will slay him.”
“Dude, I dunno, I just spared King Mark. It seems petty to kill Andred if we’re letting Mark live.”
Somehow this argument convinces Kay, so they just frog-march Mark and Andred back to Tintagil and turn them over to the custody of Sir Dinas. Afterwards Kay and Gaheris ride the hell out of Cornwall!
Along the road they bump into Launcelot, last seen in Chapter 36 chasing Pitiless Bruce with Dame Bragwaine. Kay fills Launcelot in on their whole adventure, clarifying that Tristram hasn’t been seen in Cornwall in since Chapter 22. Launcelot smiles when he hears about what a dick King Mark is, and says hard it is to take out of the flesh that is bred in the bone, which I think translates from 1460-talk to present-talk as a familiar expression about leopards and spots.