The Unknowns: A Mystery


In a trailer park called Adjacent, next to the Folsom Energy Plant, people have started to vanish, and no one seems to care. At first Lady Di and her best friend, Tom Jones, barely notice the disappearances—until their beloved math tutor, Mrs. Clarke, is abducted, too. Mrs. Clarke has left them clues in the form of math equations that lead them all over the trailer park, through hidden tunnels under “Mount Trashmore,” and into the Folsom Energy Plant itself, where Lady Di and Tom Jones and a gang of other misfits...

See more details below
$14.33 price
(Save 20%)$17.95 List Price

Pick Up In Store

Reserve and pick up in 60 minutes at your local store

Other sellers (Hardcover)
  • All (32) from $1.99   
  • New (6) from $10.28   
  • Used (26) from $1.99   
Note: Kids' Club Eligible. See More Details.
Sending request ...


In a trailer park called Adjacent, next to the Folsom Energy Plant, people have started to vanish, and no one seems to care. At first Lady Di and her best friend, Tom Jones, barely notice the disappearances—until their beloved math tutor, Mrs. Clarke, is abducted, too. Mrs. Clarke has left them clues in the form of math equations that lead them all over the trailer park, through hidden tunnels under “Mount Trashmore,” and into the Folsom Energy Plant itself, where Lady Di and Tom Jones and a gang of other misfits uncover the sordid truth about what’s really happening there.

F&P level: Y

Read More Show Less

Editorial Reviews

Publishers Weekly

This first novel's promising premise-Carey (a New York Times science reporter) uses mathematical equations and theorems as clues to a mystery-sinks under the weight of burdensome plotting and characters' hypothesizing. Spearheading the sleuthing are Di and Tom, seventh-grade misfits determined to find Mrs. Clarke, a kindly neighbor who helps them with their math homework, after she vanishes. The kids live in a bleak trailer park located beside an underground nuclear plant, made all the more unsavory by the nearby dump, Mt. Trashmore, "an entire rotting universe, reeking like sugary vomit." Deciphering notations left by Mrs. Clarke, the kids draw a map that leads them to underground tunnels, which they suspect hold the key to the woman's disappearance. The maps-simple diagrams that grow as information is uncovered-help elucidate their discoveries, yet digressions and a steady stream of data ("The Trashmore entrance was eight hundred yards above the x-axis. But the tunnel angled inward one hundred yards for every four hundred it moved downward") may dampen interest in what feels like an extended, if adventurous, story problem. Ages 10-up. (Apr.)

Copyright © Reed Business Information, a division of Reed Elsevier Inc. All rights reserved.
Children's Literature - Kathleen Foucart
In Folsom Adjacent, a trailer park town that is not even important enough to have its own name, Di and Tom notice people are disappearing. They don't think much of it until their math tutor, Mrs. Clarke, is taken, too, leaving behind a strange equation: 3 + 4 = 5. The kids take the clue and run. Soon they realize they are being pursued by agents from the Folsom nuclear power plant. The two friends are pulled into a dangerous mystery made up of mathematical clues left by their tutor and begin enlisting other kids in town to help them. With the fate of their whole town at stake, can they brave the tunnels under their trailer park and find a way to save Mrs. Clarke? It is refreshing to see a book for this age range that takes place somewhere outside a major city or a middle class suburb, though a little too much time is spent on the school lives of Di and Tom when not much of the plot takes place there. While kids who already enjoy math might like being able to figure out the puzzles throughout the novel, the constant stopping of the plot for graphs and circles could put some readers off. Reviewer: Kathleen Foucart
VOYA - Amy Luedtke
Preteen outsiders Tom Jones and Lady Di do not exactly fit in. Quiet Tom sees the world in strange colors and patterns whereas overweight Di constantly twirls her wrist when she is nervous. The friends think their biggest problem will be starting middle school in the fall and having to face the bullies and gangs that await them until their elderly friend Mrs. Clarke disappears. Why was there blood in Mrs. Clarke's abandoned trailer? Were the straws Mrs. Clarke left behind clues? As Di and Tom unravel the mystery, they discover their strange but sleepy little town of Folsom Adjacent (actually just a trailer park named after the nuclear plant where most of the adults work) hides many sinister secrets in the terrifying tunnels under the power plant. Di and Tom take on the corporate conspiracy that threatens their town with the help of other Adjacent misfits and Mrs. Clarke's enigmatic mathematical clues. Successfully working in the concepts of pi and the Pythagorean theorem into an adventure story is no easy task, but for the most part Carey succeeds because of his lively and unique writing. Readers can skim over the math puzzles and still follow the action. Adjacent is a sad and weird but fascinating place populated by strange yet completely believable and compelling characters who bravely face both inner and outer demons. Reviewer: Amy Luedtke
School Library Journal
Gr 6–8—This clever and unusual mystery is tailor made for young mathematicians. Lady Di and Tom Jones live in Folsom Adjacent, a godforsaken trailer park named after the giant power plant that shares the small coastal island. When people start vanishing from this nuclear nowhere, the two 11-year-olds investigate, using mathematical cues left behind by their missing math tutor. Equations, right triangles, pi, coordinates, and slope help the kids and some of their similarly outcast friends negotiate a massive maze of underground tunnels to access the plant and discover a nefarious scheme that will destroy the island. Carey is particularly adept at creating setting: the landscape is raw, desolate, and nearly apocalyptic. Math moves the plot along, at times at the expense of character development. Replete with diagrams, charts, and illustrated problems, the book will appeal especially to kids who love geometry, but it will also reel in fans of less numbers-centric books such as Eric Berlin's The Puzzling World of Winston Breen (Putnam, 2007) or Ellen Raskin's The Westing Game (Puffin, 1992).—Connie Tyrrell Burns, Mahoney Middle School, South Portland, ME
Kirkus Reviews
On the circular island where the Folsom Nuclear Plant is located, there sits a trailer park called Folsom Adjacent; not surprisingly, many of its colorfully boring residents work at the plant. Eleven-year-olds Diaphanta (Lady Di) and Tamir al-Khwarizmi (Tom Jones) get their wish for something exciting to happen when adults start vanishing from the population. The police department of nearby Crotona doesn't seem to care much, and most adults in Adjacent either work too much or drink too much or both. When their best adult friend Mrs. Clarke vanishes, she seems to leave behind a clue in a math puzzle, which leads to another clue in a math puzzle, and suddenly Di and Tom are taking on Folsom officials to foil an evil plot with a little help from their . . . acquaintances. Carey's debut is a brainteaser of a mystery full of quirky characters. Di and Tom are plucky outsiders with low self-esteem and overactive imaginations. By the third or fourth puzzle (they get progressively more difficult) things get a bit mathematically dense, but even reluctant mathematicians will enjoy this inheritor of The Westing Game. (Mystery. 10-14)
Read More Show Less

Product Details

  • ISBN-13: 9780810979918
  • Publisher: Abrams, Harry N., Inc.
  • Publication date: 4/1/2009
  • Pages: 272
  • Sales rank: 1,464,458
  • Age range: 10 - 14 Years
  • Lexile: 760L (what's this?)
  • Product dimensions: 5.80 (w) x 8.40 (h) x 3.30 (d)

Meet the Author

Benedict Carey, a former Los Angeles Times writer and current New York Times science section writer, was a math and physics major in college, so he knows his geometry. Hoping to ignite a passion for math in his own kids, Benedict decided to craft a smart and action-packed story for middle-grade readers that uses math lessons to solve the mysterious disappearance of their math tutor. He and his wife and children live in a suburb of New York City.

Read More Show Less

Customer Reviews

Be the first to write a review
( 0 )
Rating Distribution

5 Star


4 Star


3 Star


2 Star


1 Star


Your Rating:

Your Name: Create a Pen Name or

Barnes & Review Rules

Our reader reviews allow you to share your comments on titles you liked, or didn't, with others. By submitting an online review, you are representing to Barnes & that all information contained in your review is original and accurate in all respects, and that the submission of such content by you and the posting of such content by Barnes & does not and will not violate the rights of any third party. Please follow the rules below to help ensure that your review can be posted.

Reviews by Our Customers Under the Age of 13

We highly value and respect everyone's opinion concerning the titles we offer. However, we cannot allow persons under the age of 13 to have accounts at or to post customer reviews. Please see our Terms of Use for more details.

What to exclude from your review:

Please do not write about reviews, commentary, or information posted on the product page. If you see any errors in the information on the product page, please send us an email.

Reviews should not contain any of the following:

  • - HTML tags, profanity, obscenities, vulgarities, or comments that defame anyone
  • - Time-sensitive information such as tour dates, signings, lectures, etc.
  • - Single-word reviews. Other people will read your review to discover why you liked or didn't like the title. Be descriptive.
  • - Comments focusing on the author or that may ruin the ending for others
  • - Phone numbers, addresses, URLs
  • - Pricing and availability information or alternative ordering information
  • - Advertisements or commercial solicitation


  • - By submitting a review, you grant to Barnes & and its sublicensees the royalty-free, perpetual, irrevocable right and license to use the review in accordance with the Barnes & Terms of Use.
  • - Barnes & reserves the right not to post any review -- particularly those that do not follow the terms and conditions of these Rules. Barnes & also reserves the right to remove any review at any time without notice.
  • - See Terms of Use for other conditions and disclaimers.
Search for Products You'd Like to Recommend

Recommend other products that relate to your review. Just search for them below and share!

Create a Pen Name

Your Pen Name is your unique identity on It will appear on the reviews you write and other website activities. Your Pen Name cannot be edited, changed or deleted once submitted.

Your Pen Name can be any combination of alphanumeric characters (plus - and _), and must be at least two characters long.

Continue Anonymously

    If you find inappropriate content, please report it to Barnes & Noble
    Why is this product inappropriate?
    Comments (optional)