The Watermelon — Michael Laser

Jenny Fox goes to South America to build a school in her grandfather's country - but her summer adventure turns into much more than community service when she meets Nelson, the charismatic leader of the project.
 
Jenny isn't the only one with her eyes on Nelson. As she and her flirtatious rival get closer to Nelson, though, she discovers his dark side: an ugly prejudice against his country's enemies across the border. She doesn't want to lose him,
but how can she accept his bigotry?
 
While love and conscience clash inside her, a real war threatens to break out around her. This is a summer she'll remember for the rest of her life.