In this world of miracles, Conrad is an atheist - he sees the same phenomena, but sees no need to attribute them to a Deity ... until his first really successful opera gets the opera-house struck by the lightning bolt of God's disapproval ...
... And Conrad comes to the attention of the Prince's Men, a powerful secret society, who are trying to use the magic of music to their own ends - in this case, an apocalyptic blood sacrifice.
Life is about to get interesting for Conrad.