The Riddle of the Sphinx (Inside No. 9) was characterised by Pemberton as a thriller in the style of Anthony Shaffer's 1970 play "Sleuth", while Shearsmith identified the episode as particularly theatrical, in the style of "Sleuth" and Ira Levin's 1978 play "Deathtrap". BBC executives, according to Shearsmith, saw the episode as a cross between "Sleuth" and Willy Russell's 1980 play "Educating Rita" that read as if it had been authored by psychopaths. The executive producer Jon Plowman suggested that the first half of the episode plays out like a radio play. The word-play and tea-drinking in this part of the episode are, in the writers' opinion, very
Rita Atria Falcone had been killed. Rita wrote in her diary: "You have died for what you believed in, but without you, I too am dead." A week later Rita locked herself into the apartment and wrote a note, which said: "I am devastated by the killing of Judge Borsellino. Now there's no one to protect me, I'm scared and I can't take it any more." Then she threw herself out of the window. Many people regard Rita as a heroine because of her willingness to sacrifice everything, including the affection of her mother (who after her daughter's death destroyed her tombstone