Adrian Monk: Okay, here's what I think happened. Last Thursday, Rita was baking three pies for the town centennial. She probably put them on the counter to cool. Her husband came home. They had a fight. Maybe Pat was threatening to leave. Who knows? But there was a struggle. My brother said he heard four shots from a nine-millimeter pistol. If that's true, the shells were ejected from the gun as he fired. They must have gone flying all over the kitchen. At some point, he was interrupted. It was someone from the town coming by to collect the pies. Later, when he started cleaning up the kitchen, he got the shock of his life. One shell casing was missing. The gun is registered, so if anyone had found that casing, it would have been easily traced. It wasn't in pie number one or pie number two. It has to be in here.