Luigi Valdarno

In the short story The Adventure of the Cheap Flat, Luigi Valdarno was a junior official in a U.S. government department who was suspected of stealing some important Naval plans showing the details of some important harbour defences. He disappeared from his place of work and was found dead two days later on the East Side of New York, having been shot dead. The papers were not with him and suspicion next fell on a woman he had been going out with, a concert singer named Elsa Hardt who was believed to be an accomplished international spy.

Poirot later told Hastings that Valdarno probably belonged to the Mafia or the Camorra or some other Italian secret society which explained why an Italian assassin was sent to hunt for Elsa Hardt in London.

Portrayals
Luigi Valdarno was played by Nigel Whitmey in the film adaptation of The Adventure of the Cheap Flat in Series 2 of ITV's Agatha Christie's Poirot. In the adaptation he did not steal plans of harbour defences but rather plans for a new design of submarine.

In the NHK's anime adaptation The Riddle of the Cheap Flat, the character of Luigi Valdarno does appear. There is no voice credit as the character does not have a speaking part--this segment is mostly narrated by Poirot as a voice over.