I'll Be There is about coincidence and love and destiny. It's about how what one person does affects other people, almost in a domino effect.
Both Sam and Riddle are being raised by a very unstable father who hears voices that tell him he is in danger and must move to yet another town. The boys don't go to school, and, in fact, must take care of their daily needs themselves. They must find their own food and keep away from their father as much as possible.
Their life is pretty much surviving from day to day - until Sam meets Emily. Although there is certainly romance in this book, boys will also be pulled into this novel because there is adventure and danger and tension until things are wrapped up at the end. I think mature readers, especially, will appreciate the nuances in I'll Be There.