Here's a brief summary:
* David is on the run from Saul, who is trying to kill him.
* David seeks refuge in the Philistine city of Gath.
* Fearing the Philistines will hand him over to Saul, David decides to feign madness.
* He acts irrationally, scribbling on the city gates and letting his saliva run down his beard.
* The Philistines, believing he is truly insane, let him go.
This story demonstrates David's resourcefulness and cunning in a moment of crisis. It also reveals the complex relationship between David and Saul.