In the short story Yellow Iris, Stephen Carter is a member of the British diplomatic service.
Some four years before the events in the story, he had been posted to the British embassy in New York and had been at the dinner hosted by Barton Russell where his wife Iris had died. Barton accused Carter of having murdered her. Barton claimed that Iris had been in love with Carter and wanted to go away with him. Carter was, however, more concerned about his career and didn't want a scandal and so he poisoned her.
In the denouement, it was not established conclusively how Iris had died. Pauline Weatherby, Iris's sister hated Carter. She believed was because of Carter that Iris either committed suicide or else Barton had poisoned her out of jealousy.
Portrayals[]
Stephen Carter is played by Hugh Ross in the film adaptation of Yellow Iris in Series 5 of ITV's Agatha Christie's Poirot. His background is different in the adaptation. He is not a diplomat but Barton's partner in the Sovereign Oil company which had bribed General Pereira to obtain a oil concession in Argentina. There is no suggestion in the adaptation that Iris and Carter had a relationship.