Assimilate by Emily Jack Hayden

"Description"
Sixteen-year-old Tan Michaels is pumped to have been chosen for his new assignment: to assimilate with students at the local high school. Tan's assignment is the first major step in his secluded society's overall plan to integrate with their local California community. His genetically enhanced mind and body make the transition easy at first- Tan breezes through his homework and stuns the judges and onlookers at his first gymnastics meet. He's also managed to capture the attention of Paisley, an artsy barista he discovered in history class. He feels less fortunate to have also captured the attention of Whitney, the girl his new friends say he should want.

When Tan's twin sister goes missing, he's ordered to put his assignment on hold along with his still-new relationship with Paisley. In the search for his sister, Tan secretly discovers some mind blowing information. Has the society's long-established goal of complete assimilation morphed into something much more sinister? When his new high school friend, Cole is found dead, Tan must face the possibility that the high commanders in his own beloved society may have had something to do with it.

With forty-eight hours to figure it all out, Tan and his posse find themselves faced with choices not merely of life and death, but of who lives and who dies. And the rot at the top may be closer than Tan would ever have imagined.

"Review"
This book was entirely unexpected. I wasn't sure that I'd like it at all but oddly enough I did enjoy reading it. It is your usual science fiction. There is a secluded society living beneath our world and is scientifically far more developed. But they have their own rules by which they live. These rules are questioned when one sixteen year old is assigned to assimilate with students above ground. From there a series of events occur thus changing his view of his own world and made him think about life and what's important in it.
All the characters are beautifully written, there is some suspense and mystery as well, all in all it was a great book which every science fiction fan will enjoy immensely.