Built around a ripe conceit—wealthy matriarch scatters cryptic clues to a mysterious fortune around the globe—this first installment in a projected 10-book series is tons of fun. Lead-off hitter Riordan (<EMPHASIS TYPE=""ITALIC"">The Lightning Thief) mixes just the right proportions of suspense, peril and puzzles in a fast-paced read (Riordan mapped the narrative arc for all 10 volumes, but other high-profile authors will be writing for the series, too). Likable orphans Amy and Dan Cahill have moxie (plus Dan can memorize numbers instantly) and frailties (Amy hates crowds). As the siblings compete with less honorable members of the Cahill clan, all distantly related to Benjamin Franklin, to win the fortune by collecting all 39 clues (only two are found in this first book), they learn about their dead parents, each other and world history. The humor is spot on—one uncle is credited with inventing the microwave burrito. The only flaw? The story does not end so much as drop off a cliff. (The second book, <EMPHASIS TYPE=""ITALIC"">One False Note by Gordon Korman, is set to arrive in December.) While waiting, readers can collect cards, each of which contains evidence, and play the online game (www.the39clues.com), for which Scholastic is offering over $100,000 in prizes. This ought to have as much appeal to parents as it does to kids—it's Webkinz without the stuffed animals, and a rollicking good read. Ages 9–12. <EMPHASIS TYPE=""ITALIC"">(Sept.)

Gr 4-7 When their beloved Aunt Grace dies, Dan, 11, and Amy, 14along with other Cahill descendantsare faced with an unusual choice: inherit one million dollars or participate in a perilous treasure hunt. Cahills have determined the course of history for centuries, and this quest's outcome will bring the victors untoward power and affect all of humankind. Against the wishes of nasty Aunt Beatrice, their reluctant guardian since their parents' deaths, Dan and Amy accept the challenge, convincing their college-age au pair to serve as designated adult. Pitted against other Cahill teams, who will stop at nothing to win, the siblings decipher the first of 39 clues and are soon hot on the historical trail of family member Ben Franklin to unearth the next secret. Adeptly incorporating a genuine kids' perspective, the narrative unfolds like a boulder rolling downhill and keeps readers glued to the pages. As the siblings work together to solve puzzles and survive dangers, they develop into well-drawn individuals with their own strengths and personalities. Supporting Cahill cast members come across as intentionally exaggerated caricatures, adding to the tale's breathless fun. The book dazzles with suspense, plot twists, and snappy humor, but the real treasure may very well be the historical tidbits buried in the story. Part of a multimedia launch including a Web site, collectable game cards, and a 10-title series (penned by different authors), this novel stands solidly on its own feet and will satisfy while whetting appetites for more. Joy Fleishhacker, School Library Journal

In a bold leap forward in marketing strategy, this first book in the 39 Clues series introduces readers to what promises to be a sensational mix of reading, online gaming, card-collecting, and even a grand-prize sweepstakes. The premise of the book: Grace Cahill, matriarch of the world's most powerful family, dies and leaves behind a challenge to her descendants. They can either inherit one million dollars, or forgo the money and receive the first of 39 clues that will lead them on an around-the-world adventure in search of, well, that's a secret. But it's an earth-shattering secret, and with 10 books planned for the series (each by a different author), it had better pay off in the end. Riordan, who has plotted the main arc for the series, gets the ball rolling nicely with likable brother-and-sister heroes, a cast of backstabbing relatives, and a smattering of puzzles and clues to decipher in the quest for the ultimate secret. Whether this intriguing book represents the first major event in a shifting world of publishing, or is simply a clever money- and attention-grabbing ploy remains to be seen, but it will be fascinating to see what kids make of it. (Library edition does not include game cards).

Amy and Dan (and their au pair) are just one team among many in ruthless pursuit of a hidden family treasure, the nature of which will probably not be revealed anytime soon in this projected ten-book series, card-collecting extravaganza, and sweepstakes. Synthetically packed with flights to Paris, double-crosses, and desperate escapes, the book mistakes busyness for excitement, but it's readable enough.

"Synergy" is the name of the game in Scholastic's post-Potter search for market share. Grace Cahill has died, and her orphaned grandchildren Amy, 14, and Dan, 11, are among the heirs offered a choice: They can accept one million and walk, or they can take the first clue in a worldwide scavenger hunt to find the secret that has made the extended Cahill family the most powerful family in world history. Every other heir is out to get Amy and Dan, Grace's supposed favorites, as they work their way through the puzzles in this first volume of a ten-book "multi-platform" series. Six trading cards come with each trade-edition copy, and more can be purchased separately. Cards can be entered on an accompanying website, where readers six to 14 can "enter the race" by playing mystery games. Each new volume, by such authors as Gordon Korman and Peter Lerangis, spawns a new contest with real cash prizes. Librarians should be careful to purchase card-free library editions to avoid circulation headaches. (Novelty/fiction. 9-14)