The story Jack tells at the end is a version of "Appointment in Samarra", by John O'Hara, and the epitaph by W. Somerset Monaghan. It has also been used in an episode of 'Supernatural' with that same title (2010) and "The Six Thatchers" episode of 'Sherlock '(2017). Among other changes, Jack alters the servant's destination from Samarra to Baghdad.