Hersheimmer had left for Constantinople at a moment's notice if he fancied that a clue to his cousin's disappearance was to be found there.
Hersheimmer will never leave to find out about his cousin.
mnli hypothesis: Hersheimmer will never leave to find out about his cousin. premise: Hersheimmer had left for Constantinople at a moment's notice if he fancied that a clue to his cousin's disappearance was to be found there.