Jean Moncrieffe

In the short story The Lernean Hydra, Jean Moncrieffe is the dispenser working for Dr Charles Oldfield in the village of Market Loughborough in Berkshire. At the time of the events in the story, Jean had been working for Dr Oldfield for some three years. After the wife of Dr Oldfield died, rumours began to circulate in the village that he had poisoned her because he was in love with Jean. In her interview with Poirot, Jean admitted that she was in love with the doctor but he had not asked her to marry him because she had "choked him off". She thought that if everyone knew that there was no question of marriage between her and the doctor, the rumours would die down, but they did not.

Jean was described as a tall girl with copper-coloured hair and steady blue eyes.