You've read about Maggie, Sunita, and David. This book is about Brenna, and manatees.
Manatees are large marine mammals.
They look something like floating elephants. They're related to elephants, too, as well as to aardvarks and hyraxes. She loves manatees. Now she gets to travel by airplane to Florida with Dr. Mac and her two granddaughters, Maggie and Zoe, to work in a rescue mission for manatees. She takes along her camera with its zoom lens, and she can't wait to meet Dr. Mac's former pupil, Gretchen, who runs the rescue mission.