Just a wonderful story, set shortly after World War II.
Philippa Hunter, a timid, artistic teenager, must attend a Swiss boarding school while her father, a professional painter, travels Europe. Philippa ("Flip" to her family) knows this year is going to be horrible. She's never been able to make friends – she's awkward both socially and physically, more so than ever thanks to a kneecap shattered in the car accident that killed her mother the year before. She's always clung to her family, and now she's going to be on her own for the first time in her life.
Spoiler alert: The girl who's convinced she has no courage at all finds enough to perform a truly heroic act for the sake of someone she cares about. The unpopular girl becomes one of the best-liked kids in her class, not by getting a spiffy new haircut and attitude but by sharing her artistic gifts. The klutz finds a sport she can enjoy and excel in. The motherless girl who's never talked to a boy in her life finds friendship and more in a young man who teaches her that being able to remember a lost loved one is a precious gift.
The prose here isn't as luminous as that in L'Engle's Camilla,
but there's also no horrifying sexism. The love story makes you want to cheer. And the dialogue is terrifically funny. Also, Flip's relationship with a particular teacher reminds me a great deal of some scenes in Jane Eyre.
If you like the sound of a good old-fashioned young adult novel that stands up perfectly to the test of time, read this book.