Diane decides to make her connection to Oliver temporarily permanent and the couple exchanges "vows" on sacred ground. They begin their "honeymoon" at an inn with a proprietress who is delighted to play along. Next day at Hadrian's Wall, their union is blessed with the surprise appearance of a son. They plot their next move when Oliver discovers that Aristotle is giving them clues to the mystery in the crosswords. (thetvdb.com)