Lone Star by Paullina Simons

Falling in love was the easy part ...
Chloe is weeks away from college when she embarks on a grand European adventure with her boyfriend and two best friends. Their destination is Barcelona, with its promise of romance and mystery, but first they must detour through the historic cities of Eastern Europe to settle an old family debt.
As they traverse the unfamiliar landscape of the post-Communist world, Chloe meets a boy on a train who is going off to war. Johnny carries a guitar, an easy smile - and a lifetime of secrets.
The trip becomes a treacherous journey into Europe's and Johnny's darkest past - a journey that threatens to shatter the bonds holding together four lifelong friends. And Chloe must choose between her deepest desires and the future she thought she wanted.

Very good condition.