Who dunnit?

Yes, yet another night at the theatre for isbi and isbiJG, this time an Agatha Christie in Sydney CBD. I had the culprit nailed after 30 minutes but they got knocked off soon after the interval. I soon narrowed it down to a couple of other possibilities but in the end, Agatha beat me again.
It kicked off at 6pm which would have meant dinner at about 5. No chance of that so by the time we’d caught the train back over the bridge, I was getting a bit hypoglycaemic. Fortunately there’s always one of our Italian compatriots ready to help out (see extra).