The Girl in the Punchbowl: A Pete Schofield Caper, by Thomas B. Dewey (epub/Kindle/pdf)
"Thomas B. Dewey is one of detective fiction's severely underrated writers!" -- Bill Pronzini
Pete Schofield had been to art-colony parties before. Usually they were all the same, but this one had an added kick. A giant punchbowl, filled to the rim with champagne, and spiked with the barest, most beautiful mermaid he'd ever seen. He was enjoying every inch of it. So was everyone else, until some joker decided to plunge into the act. That's when the lights went out, the lady disappeared, and Pete got hot as a pistol!