In the novel Ordeal by Innocence, Leo Argyle is the husband of Rachel and the father of all the adopted children who at one time or other, had their home at Sunny Point. An Oxford don, he first met Rachel at a social club in London's East end. They were drawn together by a share common interest interest in social welfare both felt that there was so much that needed to be done and so much that could be done. After the marriage Rachel plunged herself and her inherited wealth into philanthropic concerns. While Leo supported her he had a ironic sense of realism Which made him doubt whether work which was worth doing was always as successful as it ought to be. Rachel had no such hesitation hesitation and because she was able to unable to have children, her great passion became various schemes to help children in need. She adopted children and during the 2nd World War also turn her home at Sunny Point Into a hostel for children who have been evacuated.
As looking after children became more and more the centre of Rachel's life, Leo found himself largely abandoned and he began to focus primarily on his academic interest researching into historic medieval economics. Over time Leo became drawn to his secretary Gwenda Vaughan. As Leo reflected after Rachel's death, he had been drawn to rachel because of her warmth of heart but the tragedy was that that warmth of heart had not really been for him but for children.
In that respect Rachel's murder being attributed to Jacko Argyle was convenient and at the time of the events in the book, two years after Rachel's death, Leo and Gwenda had already made arrangements to be married quite soon. However when when Jacko was found innocent and the police reopened the murder case Leo found himself in a quandary and had to put the marriage plans on hold. To proceed with them what only remind the police that he had a motive in wanting Rachel's death. Moreover he also knew that neither Gwenda nor himself had an alibi for the time of the murder. Indeed for a time Superintendent Huish did consider Leo or Gwenda to be the prime suspects because they were the only ones with a clear motive. There was also a strain between Leo and Gwenda caused by the mutual suspicion that the other had committed the crime. Of the many characters in the book, Leo can be considered as one who suffers most an "ordeal by innocence".
Leo had for so long been in the shadow of his wife that Arthur Calgary's first impression of him was that he was "so attenuated, so transparent, as hardly to be there at all. A wraith of a man".