Former big name stage stars Edward Mulhare and Eleanor Parker are appearing in a play near Cabot Cove that Jessica Fletcher and her late husband did in community theater many years ago. Of course the cosmopolitan Jessica knows these two and also knows that they've been on the rocks so to speak as a couple. Kind of like Douglas Fairbanks and Mary Pickford back in the day.
So when soap star Ann Turkel goes on in Parker's place after a quarrel and Turkel is found dead later of cyanide poisoning it's Parker looking good for it.
Stealing this particular episode is John Schuck who is the police chief and part of the community theater. Amos Tupper apparently has a lot more to do in Cabot Cove than Schuck ever did. In his first murder case the frustrated ham morphs into Hercule Poirot. Schuck really is funny in the part, more like Clouseau than Poirot.