David comes across a priest who is suspicious that he's alone. He lies to him that he's running secret errands for the king and meeting his men later. He asks him for bread. The priest explains the bread is holy, and only people who haven't had sex recently can eat it. David assures him it's been at least three days. He also asks for a sword. The priest happens to have Goliath's sword, which will do. A couple of foreigners approach, star-struck, and ask if he's David. He pretends to be crazy in order to get them to take them to their country, where the king asks them why the hell they brought him a crazy dude.
David leaves the foreign court and goes and hides in a cave. People soon hear about the crazy dude in the cave and start joining him. He's Robin Hood: every one that was in distress, and every one that was in debt, and every one that was discontented, gathered themselves unto him; and he became a captain over them: and there were with him about four hundred men (v. 2). He approaches the king of Moab and begs refuge for his parents.
Gad the prophet tells David to leave Moab and go to Judah, where he lives in forest.
Saul, meanwhile, hears that David has been sighted and rebukes his cronies for letting him escape. One of them happened to observe the transaction with the priest and pipes up. Saul calls the priest and his entire family to him. The priest insists that David is loyal. Dumb move, because Saul orders his execution. His servants refuse, save the one who accused them in the first place, Doeg. He kills 85 people. Then he goes to their city, Nob, and kills every living thing in it. Every tyrant needs a psychotic enforcer, I suppose.
One priest, Abiathar, escapes and gets to David. David says he saw Doeg that day, and knew he would tell Saul, and blames himself. Why didn't he say something then, even if it was just to avoid the guilt? Anyway, David promises to protect