He'll rescue Princess Judith of course. I'm not sure if he's rescued any princesses before, but he probably has. That's even better than rescuing maidens. After she's rescued, Princess Judith won't have to cry any more. Maybe Sir Lancelot will marry her instead of Guinevere. I think she's prettier than Guinevere.
Hey! Guess what! I've just heard Sir Lancelot's armour rattling somewhere near by and I've had a look out the window. His horse is down in the car park, chewing at some of the leaves in the flower-bed. You can see it by the light of the big lamp in the middle.