Six one-hour episodes of the American TV drama following a nun and an astrophysicist into investigations of the unknown. Dr Richard Massey (Bill Pullman) is a scientific minded man who believes there is nothing that cannot be explained by science. Sister Josepha Montafiore (Natasha McElhone) is a nun of the holy order who believes almost exclusively in that which cannot be seen or touched - faith. The two must find common ground as they are cast together in an investigation into signs that that may or may not mean that the biblical 'End Of Days' is at hand. They find that Isaiah Haden (Michael Masse), a noted Satan supporter, is in the process of calling forth an unholy storm of darkness upon earth.