An unknown person sets off explosions in London. After a subway bombing leaves victims, Zack and his team are brought in to try to understand how the terrorist works - but there are few clues, and they don't know where or when the next strike will occur. A recently arrested teenager claims to know the answer, but before Zack can ask, the guy is shot and falls into a coma. Will Zack be able to crack the code before another explosion occurs?