The Color of Air by Gail Tsukiyama

 A couple of reviewers on Amazon said the author didn't get all the Hawaii-related details correct. But that didn't stop me from loving this book. It's set in Hawaii from about 1900 to the 1930s in the town of Hilo and on a local sugar cane plantation. Daniel, a son of Hilo, has returned from Chicago, where he became a doctor. One of his cases went sideways and he wanted to return home to figure out what to do next. He arrives home just as the local  volcano is erupting, which has everyone on edge, as the lava flow may change direction and head toward Hilo. He runs into his high school girlfriend, Maile, who has returned home with her own secret after venturing away from Hilo.

The other main character is Daniel's Uncle Koji. He fell for Daniel's (now deceased) mother the first time they met--but she had eyes only for the flashy Franklin. We learn the story of this trio in flashbacks.

I love the characters--main and supporting--in this book as well as the unique setting. Couldn't put it down.