Jessica Fletcher is becoming quite the globetrotter now and apparently has relatives in all kinds of places. She's in the midwest now and visiting niece Anne Kerry and her husband James Stephens who happens to be a police detective.
While there the whole group which includes two kids go to the opening of a new theme park based on horror stories. The creator of this place and other like it is James Coco whose genial public persona is a total lie. He's a ruthless businessman and when he dies no one is really mourning.
But he died in a locked room, underground and bolted from the inside. Coco's less than grieving widow Christine Belford actually hires Angela Lansbury to prove it was murder rather than suicide.
It's all in the how here, but when the crime is revealed in flashback it was really way too clever in the cover-up because we also see the murder was quite spontaneous. The perpetrator is clever, but I can't believe that clever.
Still locked room murders are always intriguing.