This was a great story of survival, sisterhood, and love. The story starts with a ship(boat)wreck and it's survivors - Emma & Henri Jones and a boy named Alex they had just met while on vacation in Puerto Rico. Alternating with the story of their attempts to survive on a deserted island is the story of how Emma & Henri's close relationship as sisters fell apart just months and weeks earlier. 
 I loved Taylor's ability to write the complexities of the sister relationship, from codependency to blind hate bordering on life-threatening... that probably sounds extreme but once you get a chance to read it, you'll understand what I mean.