The city of Venice is alive with celebrations for Redentore, the most spectacular festival of the year. The streets are lined with revellers eating and drinking, and boats travel along the canals into the bacino of San Marco in anticipation of the firework display. It's going to be a night to remember, and all the more so for Nathan Sutherland and his wife Federica, who have been invited to an exclusive party in the company of the British Ambassador. The festivities take a turn, however, when Nathan suddenly finds himself struggling for breath and is rushed to hospital. Tests show he has all the symptoms of aconite poisoning, a toxin derived from the deadly wolfsbane plant. An unfortunate accident? Or a deliberate attempt to poison him? As Nathan investigates, he discovers many guests might just have had a motive for murder . . .