Donna Leon, for instance, allows her readers the vicarious pleasure of walking the streets of Venice with her detective, Commisario Brunetti and savouring the insalata caprese, with mozzarella, that he eats with his family in the cool of the evening.

In Trace Elements, the 29^th Brunetti mystery, it's summer in Venice and the heat is oppressive. Even in the Questura "the temperature was almost as bad as it was outside, the humidity certainly worse. The new city administration had cut back on spending for the public services, and the allowance for electricity was not sufficient to provide air conditioning for the entire palazzo."

Brunetti wonders why tourists come to the city in July and August because "every Venetian who could, left". He watches the crowds on the Rialto where the sun "beat down on their already-burnt faces, sweat battered their backs and shoulders, exhaustion closed in on them from behind".

Brunetti and his colleague Claudia Griffoni respond to a call from the Fratebenefratelli hospice, where a dying woman wants to speak to the police. Benedetta Toso, distressed at the recent death of her husband, Vittorio Fadalto, in a motorcycle accident, believes he's been murdered. She hints he took "bad money" to help pay for her treatment and that as a result "they killed him". Brunetti assures Benedetta, as she dies, that he will investigate the accident.

Fadalto, a scientist, worked for Spattuta Acqua, "a company involved with the provision and distribution of water in the Veneto". He measured the water quality through sensors on the rivers, which feed into the lagoon. The question is, what has he discovered that has put his life at risk?

Brunetti, aided by the extraordinary skills of Signorina Ellettra Zorci, the Vice-Questore's secretary and "eminence grise" of the Questura, uncovers a tangled tale of corruption, greed, lust and a potential environmental disaster.

Leon highlights her growing concerns over the future of Venice through her detective's thoughts: the overwhelming number of tourists, the damage inflicted on the lagoon by massive cruise ships and MOSE, the $7 billion mega-project to block the major entrances of water from the Adriatic. Leon says it "has yet to give evidence it will work. It's construction appears to have done major damage to the eco system of the laguna." She worries that Venice remains a city entirely unprotected from the rising of sea waters.

However, as a result of this COVID pandemic, there are no longer tourists in Venice, nor cruise ships and the waters of the lagoon are clean enough for dolphins to return. Perhaps Leon's next Brunetti mystery will be set in a city cleansed of its own parasites.