Leading British writer Howard Jacobson, a Jew himself, examines the origins and consequences of Christian belief. He argues that although Christianity originated in devout Judaism, for Jews it has been, for the most part, a calamity. Jacobson talks to Christian and Jewish scholars. He visits Jerusalem, Bethlehem, Galilee and Rome to find out more about Jesus the Jew, and discovers how key Christian beliefs - including the notion of a Messiah and baptism - have roots in Judaism. Furthermore, he asserts that Jesus didn't intend to start a new religion, and that for Jesus's family the new movement remained within Judaism: for them he was a charismatic Rabbi. Is Judaism Christianity's guilty secret?