A Ring of Endless Light by Madeleine L'Engle is the fourth book in the Austin Family series. This is a hard summer for Vicky and her family. They are spending an extended vacation with her grandfather who is dying of leukemia, but as if that wasn't enough to deal with, one tragedy after another strikes the community. Vicky tries to keep herself busy helping out with a dolphin communications experiment, but all of the horrible things that are happening definitely take their toll on her. On top of the various tragedies, she's also got three different guys vying for her attention and she has to figure out who she really wants to be with. She spends a lot of time with her grandfather and in his illness he imparts a great deal of wisdom to her. Even that isn't enough to heal her soul though, and she can only find comfort and solace in the dolphins that she has come to know and care for.
This is a very sad book, but it's also probably my favorite in this series and I'd highly recommend it. I just love reading about the spiritual connection that the main character has with the dolphins and with the guy leading the experiment. This book can probably be read as a standalone, but would be a good idea to read the previous books in the series plus The Arm of the Starfish for background story.