Troubling a Star

In book five of the award-winning Austin Family Chronicles young adult series from Madeleine L'Engle, author of A Wrinkle in Time, Vicky Austin experiences the difficulties and joys of growing up.
After a year in New York City and a summer with her grandfather, Vicky Austin returns to the rural connecticut village she grew up in— and feels totally out of place. Then she meets Adam Eddington's Great Aunt Serena, who reminds her of her beloved grandfather, and she begins to find a comfortable, if not exciting, routine to her days. At Christmas, Serena gives Vicky a trip to Antarctica, to visit Adam. Vicky can't believe her luck.
But the trip is not what Vicky imagined it would be. First of all, she doesnt know where she stands with Adam. He's pulled back, saying they are just friends. But weren't they more than that, Vicky thinks. And Vicky's fellow passengers are not what they seem or they are more than she knows. Finally, even Aunt Serena's motives are suspect, as Vicky discovers a journal that belonged to Adam's famous uncle who disappeared many years earlier.
As Vicky becomes more and more caught up in a mystery involving drugs, nuclear waste, and international espionage, she discovers that her assumptions about the world are hopelessly naive and that life, hers included, is as fragile as the ecosystem of Antarctica, the world's most remote continent.
Books by Madeleine L'Engle

A Wrinkle in Time Quintet
A Wrinkle in Time
A Wind in the Door
A Swiftly Tilting Planet
Many Waters
An Acceptable Time
A Wrinkle in Time: The Graphic Novel by Madeleine L'Engle; adapted & illustrated by Hope Larson
Intergalactic P.S. 3 by Madeleine L'Engle; illustrated by Hope Larson: A standalone story set in the world of A Wrinkle in Time.
The Austin Family Chronicles
Meet the Austins (Volume 1)
The Moon by Night (Volume 2)
The Young Unicorns (Volume 3)
A Ring of Endless Light (Volume 4) A Newbery Honor book!
Troubling a Star (Volume 5)
The Polly O'Keefe books
The Arm of the Starfish
Dragons in the Waters
A House Like a Lotus
And Both Were Young
Camilla
The Joys of Love