Four exceptionally tech-savvy kids are recruited by the government to guard against the mysterious archcriminal Shantorian. As with the first book, the story is told through a series of interrogations of the tracker Adam Henderson by an agent who is assigned to break him. Things aren’t always what they seem, though, as we learn that one tracker may be a mole. Readers are invited to crack codes, look for clues, and watch videos on their computers. (The same information is also found in an appendix.) It is almost impossible not to be caught up in this unconventional series and its many twists and touches of humor.
— Todd Morning