And Murder for Dessert

Ellen McKenzie and her fiance, Chief of Police Dan Dunham, are on their way to the very upscale Harvest Festival Dinner, hosted by Ellen's niece, Sabrina, and her husband, Mark Tortelli. They are seasoned winery professionals. What could go wrong?
New to Silver Springs Winery, the Tortellis have been worried for weeks that their jobs depend on the success of this event, and the reputation of the guest chef hasn't helped calm their nerves.
Otto Messinger is noted for his temper tantrums. Ellen is hoping he'll keep himself in check. Dan is hoping the Tortellis, who have been staying with Ellen for a month, will triumph and soon find their own place to live.
Tonight's guest list seems to include everyone who has ever had a feud with Otto, a fact the little chef is thoroughly enjoying. The dinner progresses, a little shaky but without disaster. Then it's time for dessert. But where is Otto?
It is Sabrina who finds him, quite dead, in a wine fermenting tank. Who helped him into it? Dan seems to think it was Sabrina. Ellen would prefer Dan find another suspect--and there are plenty....