"Hell is other people," Jean-Paul Sartre famously wrote in No Exit. The fantastic tragicomedy Madah-Sartre brings him back from the dead to confront the strange and awful truth of that statement. As the story begins, Sartre and his consort in intellect and love, Simone de Beauvoir, are on their way to the funeral of Tahar Djaout, an Algerian poet and journalist slain in 1993. En route they are kidnapped by Islamic terrorists and ordered...