Cynthia, whose young spirits were naturally buoyant, was looking quite her pretty self again, and we all, with the exception of Lawrence, who seemed unalterably gloomy and nervous, were quietly cheerful, at the opening of a new and hopeful future. 
The new situation is a new business they are opening together.
mnli hypothesis: The new situation is a new business they are opening together. premise: Cynthia, whose young spirits were naturally buoyant, was looking quite her pretty self again, and we all, with the exception of Lawrence, who seemed unalterably gloomy and nervous, were quietly cheerful, at the opening of a new and hopeful future. 