William Carmichael is one of the senior lawyers at Linnet’s English law firm. After he receives a letter from Linnet revealing that she and her new husband Simon Doyle ran into Andrew Pennington during their honeymoon in Egypt, Carmichael decides it can’t be a coincidence and sends his nephew Fanthorp down to investigate immediately. Fanthorp claims to Poirot that he and his uncle were just trying to protect Linnet from Pennington’s crooked business dealings—there may be truth to this, but it’s also clear that Carmichael and Fanthorp have their own stake in Linnet’s affairs.