In the novel Crooked House, Clemency Leonides is the wife of Roger, the eldest son of the wealthy Aristide Leonides. She works as a scientist at the Lambert Institute at Gower Street, London. She is currently researching the therapeutic effects of radiation.
Roger is her second husband. Her first husband had also been a scientist who did research work on crystallography. He was not well paid, had been worked very hard, and died of tuberculosis. Roger wanted Clemency to stop working but during the war she had felt it was her duty to work and at the end of the war, felt she had to carry on.
Sophia Leonides thought that there was a ruthless streak which ran right though her family, and her aunt Clemency is no different. According to Sophia, Clemency is ruthless in a "cold-blooded impersonal way". On meeting Clemency, Sophia's boyfriend Charles Hayward is forced to agree. There is a coldress in the way she analyses the events and implications of Aristide's murder. Their apartment is also sparsely, functionally furnished. Clemency could "never be anyone but herself." She had a sharp and definite personality which Charles found alarming.
Clemency is described as a woman of about fifty, with grey hair cut very short with "what was almost an Eton Crop" but which grew beautifully on her well-shaped head. She had an intelligent seratue face with light grey eyes of a " peculiar and searching intensity".