 When he meets Rina, a young widow, during an investigation at a yeshiva in "The Ritual Bath," he is compelled to explore the religion for himself and eventually to become a religiously observant Orthodox Jew.Decker, though raised Baptist by his adoptive parents in Florida, discovers as an adult that his birth parents were Jewish, which makes him Jewish under traditional Jewish law as well.All the books in the series are rooted in, or at least include, Jewish themes.