ALA Booklist (Sat Apr 01 00:00:00 CDT 2017)

While attending a bookstore party to celebrate the publication of the long-lost Edgar Allan Poe manuscript they discovered in Book Scavenger (2015), seventh-grade sleuths Emily and James notice their social studies teacher acting suspiciously. Their first case may be over, but suddenly they're on the trail again, investigating several individual mysteries that may or may not be connected: the coded message their teacher dropped, the legendary Mark Twain cipher, and a serial arsonist whose latest fire breaks out with Emily present. Age-appropriate literary allusions include Emily reading Zilpha Keatley Synder's The Egypt Game (1967) and James referring to a simple cipher as "Nancy Drew level." Making extensive use of San Francisco history and locales, Bertman offers another involving chapter book in the Book Scavenger series, which offers a large, interesting cast of characters, plenty of challenges for code enthusiasts, and more complexity than most middle-grade mysteries. The appended author's note helps readers separate fact from fiction. Young readers captivated by these distinctive characters will be hoping for the series to continue.

Horn Book

When their teacher, Mr. Quisling, begins a furtive book quest that results in fires around San Francisco, puzzle aficionados Emily and James (Book Scavenger) try to discover who's setting the fires, while simultaneously solving a Mark Twainrelated "unbreakable code" to find treasure. Cryptographers and mystery lovers will enjoy following the clues as the smart plot and whom-to-trust character development keeps readers guessing.

Kirkus Reviews

Riddles in an online book-finding game put young cipher sleuths Emily and James on the trail of both buried treasure and a vengeful arsonist.Amid a welter of clues, codes, mysterious fires, literary references, glimpses of San Francisco sites and history, and developing relationships carried over from the 2015 opener, the tale takes a suspenseful course. It builds increasingly following Emily's discovery that her social sciences teacher, Mr. Quisling, is receiving coded clues to copies of Tom Sawyer that have been hidden around the city. The seeming game takes a sinister turn when someone (introduced to readers as "the Phoenix" in ominous interludes) torches the bookstore in which Emily loves to hang out, nearly killing her—and then an exhilarating one when Emily, who is white, and her Chinese-American best friend, James, decipher a message in a supposedly unbreakable code on a document that once belonged to Mark Twain. Bertman surrounds Emily with a supporting cast that is diverse in age and personality if not so much in race, and though the arsonist is summarily hustled off after a tidy confession, the multistranded plot does wind up to a climactic conflagration, the excavation of a glittering 19th-century trove, and broad hints of sequels to come. Brisk, bookish good fun for puzzle and code lovers. (historical afterword) (Mystery. 9-13)

School Library Journal (Wed Mar 01 00:00:00 CST 2017)

Gr 4-6This second installment leaps in right where the first left off, with middle schoolers Emily and James on the trail of a new coded mystery. Things are heating up as an arsonist called The Phoenix leaves a trail of hidden books and small fires all over San Francisco. While worrying about family finances, figuring out what their teacher Mr. Quisling is up to, taking part in a historical treasure hunt, and planning the school dance, the intrepid heroes have more than enough on their cipher-loving minds. Though the plot stands alone, readers may need to revisit the first book in the series to catch up on necessary exposition. Without the weight of explanation, though, the story speeds satisfyingly along and is, all in all, a successful sequel. Includes supplementary back matter on geographical and historical references. VERDICT Readers who loved the first volume will find this follow-up even more satisfying. Purchase extra copies where there are fans.Katya Schapiro, Brooklyn Public Library