Dead Happy — Josh Silver

The experiment continues in the dark and disturbingly thrilling conclusion to the HappyHead duology where Seb will find the secret to escaping is more heart-wrenching than he ever imagined.
 
Seb was sure surviving the experimental health center of HappyHead would be enough to send him home. But now he joins the top ten contestants in the next stage of the testing, which will take place on a remote island, under the watchful eye of a mysterious couple. 
 
Unsure if Finn is dead or alive, Seb reluctantly teams up with Eleanor again as the pair are forced to compete in a series of ever stranger trials to prove their connection and get their lives back. But Seb can't stop thinking about Finn and how he may have been too much of a threat to the program.  
 
Determined to find him, Seb's search uncovers an even darker reality…and the only way to escape the island will be to expose the sinister truth behind HappyHead once and for all.