Miss Clark

In the short story The Terrible Catastrophe, (later chapter 15 of The Big Four), Miss Clark is the companion of Mrs Templeton, the wife of the invalid Mr Templeton. Templeton's Nurse Mabel Palmer had heard him say: "They'll do for me, the four of them." When Poirot asked who she thought "the four" referred to, she said it could be Mrs Templeton, her son, Dr Treves the attending physician (whom she believes is having an affair with Mrs Templeton). The three with Miss Clark made four.