Conversation so far:
when does season 7 once upon a time start
Once Upon a Time season 7 premiered on October 6, 2017.
what day was the season 7 of once upon a time on tv
Once Upon a Time season 7 aired on Fridays.
which network was the season 7 of once upon a time on
Once Upon a Time season 7 aired on ABC.

Question: can you tell me the main story of the season
Self-contained rewrite: can you tell me the main story of the season 7 of once upon a time