Instead of 39 steps, billionaire Grace Cahill left her heirs 39 clues scattered around the world. At the end of this circuitous trail are the answers to a great family mystery, but Amy and Dan must decide whether any prize can be more important than the rescue of their missing parents. The beginning of an enthralling ten-book arc.

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 (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, 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. (Sept.)

Gr 4-7

When their beloved Aunt Grace dies, Dan, 11, and Amy, 14-along with other Cahill descendants-are 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

"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)

Grace Cahill dies and leaves her orphaned grandchildren, Amy, 14, and Dan, 11, with a choice. Do they, and other descendants, want a million dollars, or do they want a clue that will set them on a search that will change the world? David Pittu's narration stresses the adventures of the siblings’ quest as they seek clues from Philadelphia to the catacombs of Paris. Pittu's delivery enlivens the story with dialogue that portrays fearful Amy and daredevil Dan, as well as providing characterizations of their many competitors in the search. How can the two triumph over their malicious elderly uncle and devious cousins? This is the first book of a projected series of 10, written by favorite children's authors and tied to online games and the chance to win a sweepstakes. S.W. © AudioFile 2009, Portland, Maine