Wren and the Codebreaker's Notebook
A summer. A stranger's notebook. A code somebody wants kept secret. Wren has to think like a codebreaker to solve it — and so does the reader. Every cipher lands on the page for you to crack, with a no-fail safety net so no young agent ever gets stuck. Clearance awaits, Agent.
- Published
- 2025-06-09
- Format
- Paperback / Kindle
- Pages
- 113
- ISBN-13
- 979-8180601520
- ASIN
- B0H4K1RXVZ
- Age range
- Ages 9-12
- Price
- 9.99
Inside the pages
Sent to spend the season at her grandfather's lighthouse, Wren expects fog, gulls, and nothing to do — until a loose floorboard gives up a battered notebook full of ciphers, a glowing lantern key, and an invitation into the Bureau.
To follow the trail, Wren has to learn the agents' craft — shifting alphabets, hidden first letters, dots and dashes carried on the wind. Every code she cracks opens the next door.
Ten real ciphers, taught not faked.
Ten ciphers, woven into one story — not puzzles bolted to the back of the book, but the very locks that move the mystery forward. Each one appears in the story and is fully explained, with a worked example a young reader can actually do.
Caesar Shift
Slide the whole alphabet three letters along and read what's left.
A1Z26
Every letter becomes its number. A is 1, Z is 26.
Atbash
Flip the alphabet end to end — A trades places with Z.
Morse Code
Dots, dashes, and a lantern blinking across the dark water.
Acrostic
The message hides in the first letter of each line.
Mirror Writing
Backwards on the page, perfectly clear in a windowpane.
Rail Fence
Zig-zag the letters down two rails, then read straight across.
Keyboard Shift
Hop one key to the right on a typewriter's rows.
Keyword Cipher
A secret word leads the alphabet; the rest falls in behind it.
Substitution
Invent a whole secret alphabet and swap letter for letter.
Crack the code. Unlock the chapter.
Each cipher isn't a side activity — it's the next door. Crack one and the story moves forward. Don't, and you sit at the page until you do.
A story to read and a puzzle to solve — bound together.
Illustrated chapters
A full coastal mystery, carried by warm hand-painted scene art in every case.
Real ciphers in play
Each lock in the plot is an actual code the reader learns and breaks to move on.
Decoder pages & gates
Bonus activities, two challenge "gates," and a complete answer key in the back.
The screen-free puzzle kids actually enjoy.
Real thinking, disguised as a mystery
Pattern-spotting, logic, and codebreaking — the foundations of math and computer science, with none of the worksheet.
Pencil-and-paper, no devices
Everything decodes by hand. A book that earns quiet, focused time instead of a screen.
Read together or solo
Strong enough to read straight through, rich enough to slow down and solve side by side.
Book One of the casebook.
The Bureau keeps its files open. New coast, new codes, new cases — the lantern stays lit for the next recruit. Follow the series →
Olivia Marie James
Olivia Marie James writes warm, clever adventures that treat young readers as the sharp, capable thinkers they are — stories that leave a child with something real in hand.