Ed Davenport comes home fuming at his wife, claiming that a lab report says that she poisoned some of his sandwiches a couple of weeks back, and he therefore knows she poisoned her uncle so that she could inherit.
Davenport is on his way out of town on a business trip and checks into a motor court for the night. He begins to feel ill and calls a doctor who then calls his wife. Shortly after his wife arrive, Ed dies, accusing, with his dying breath, his wife of poisoning the chocolates she packed for him. The doctor locks the room and says the law dictates that he must summon the police. When the room is unlocked after the police arrive, there is no Ed. Sometime later, Ed's body is found buried in a shallow grave nearby. The odd forensic evidence here - Ed did die of arsenic poisoning, but his stomach contents were bacon and eggs with no chocolates. The doctor had pumped Davenport's stomach on arrival so the lack of chocolate makes sense, but where did the bacon and eggs come from?
Perry had been retained by Ed's wife Myrna to deal with issues concerning her estate, but that effort now transitions into defending her for murder. A couple of odd things here besides the corpse with a taste for breakfast - Myrna's constant companion is her cousin Louise. These two are always together. Why? Maybe Myrna needs somebody to talk to since Ed Davenport is a nasty unattractive man in just about every way possible. Also, when Paul is doing some sleuthing he notices somebody following him who immediately runs away when noticed.
Of course the police and the DA have come to all of the wrong conclusions, but the nice thing about Perry Mason is, not only does he get his client off, he generally provides the prosecution with the actual murderer. Hamilton Burger should be grateful, but surprisingly he is not.