Gr. 5-8. Horowitz, using the voice of M16 covert weapons specialist Derek Smithers, details the gadgets he developed for 14-year-old spy Alex Rider during his first five adventures. For each device Smithers clarifies the setting in which the contrivance was used, offers a detailed description of its operation, and provides a labeled schematic diagram. The inventions, engineered with wonderful kid-appeal, include a high-tensile yo-yo, a radio mouth brace, and an exploding ear stud. Smithers emphasizes that none of the M16 gadgets are deadly (Alex is, after all, still a boy), although he also describes Scorpia's pizza delivery assassin kit and the CIA Geiger counter games console. Horowitz/Smithers' frequently tongue-in-cheek commentary will remind young readers that these gadgets are still the stuff of fiction, although an appended glossary of scientific and technical terms makes it clear that the contraptions aren't that far-fetched. A sure bet for Alex Rider's many fans; classes teaching technical writing may also find this an interesting model.