The Calla Cress Decrypter Thriller Series

Unlock the Code-Cracking Thrills of the Calla Cress Decrypter Series

Step into the action-adventure cyber-thriller universe where ancient secrets fuel tomorrow’s digital wars. Calla Cress, British Museum curator by day, elite code-breaker by night, stands between ruthless hackers and total network domination. From the shadowy corridors of London’s tech, secret agency underground to clandestine data bunkers half a world away, Calla unravels encrypted puzzles that could rewrite history … or end it.

Perfect for readers who devour technothrillers, spy fiction, and historical mysteries, each book in the Decrypter Series fuses real-world hacking, lost artifacts, and high-octane action into an addictive ride you won’t put down. Join Calla on her globe-trotting missions, decode the conspiracies, and discover why fans call her “the smartest heroine in cyber-espionage fiction.”

Crack the first cipher today and dive into a series where every chapter raises the stakes—and the heartbeat.

Our lead character

Calla Cress - The Decrypter

Calla Cress is a curator at the British Museum in London and the head of a secret, multi-government spy organisation, the International Security Taskforce (ISTF), codenamed Red Fox. Calla embarks on action-packed adventures across the globe, often delving into historical mysteries and cutting-edge cyber threat.She is known as The Decrypter

Read Calla's Intelligence File

Our Lead Characters

Nash Shields

Nash Shields, a complex and highly skilled individual with deep ties to the world of intelligence and security. And a soft spot for Calla Cress.

Read Nash's Intelligence File

Our lead characters

Jack Kleve

The Chief of Science and Technology at the International Security Taskforce (ISTF) and a Technology Adviser with the code name White Wolf.

Read Jack's Intelligence File

The Calla Cress Decrypter Thriller Series

Introducing the Calla Cress Decrypter Thriller Series

Where Ancient Codes Collide with Tomorrow’s Cyber Wars

If Dan Brown’s Robert Langdon could hack a mainframe, and if Lara Croft swapped pistols for quantum cryptography, you’d get Calla Cress. These exciting technothrillers fuse lost history with bleeding‑edge espionage and never sacrifice heart for hardware.

Meet Calla Cress  

Artefact handler at the British Museum, government agent.  Reluctant celebrity after saving the world—more than once. Calla is the series’ razor‑smart centre, driven by loyalties forged in childhood and secrets she can’t outrun. Whether she’s decoding a Nazi‑era manuscript or out‑maneuvering a quantum hack, her first rule is simple: read the code, or the code will read you.

Ready for exciting adventure where history, technology, and espionage collide? Join the army of fans who love the Calla Cress series by Rose Sandy!

If you enjoy mystery, suspense, thrillers, action novels, or technothrillers across several continents like a Jason Bourne or James Bond movie fronted by a female protagonist, you've found your next obsession. The  Calla Cress Decrypter series delivers guaranteed action and adventure!

At the heart of the series is Calla Cress. Initially a museum curator, she becomes a cyber agent and the head of the International Security Taskforce (ISTF), a secret multi-government intelligence body funded by the UK, US, France, Germany, and Russia. Known as "The Decrypter", Calla utilises her unique knack for history and technology to decipher encrypted codes and scripts, ancient and cyber. Her personal quest for answers about her mysterious past and her long-lost parents is interwoven with her dangerous missions.

Calla is joined by her two faithful friends, Nash Shields and Jack, and together they are thrown into a dangerous journey of cyber espionage investigating the criminal, the unexplained, the scientific, and the downright unthinkable. Their adventures dip into the mysteries of our world, the fascination of technology breakthroughs, the secrets of history, and global intelligence. They pursue cryptic manuscripts like the Hadrius, infiltrate secretive digital auctions held by groups like the Blackhorse Group, investigate dangerous technologies disguised as apps, uncover the secrets of historical ciphers like the Beale Ciphers, and search for legendary lost cities. In this world, technology and science are at the forefront of humanity, and cybercriminals cripple systems and create data breaches.

What readers love about the Decrypter books is the astounding detail, especially the historic references, location descriptions, technology, and cryptography – readers agree the author "really knows her stuff".

The writing is described as brilliantly written with descriptive and detailed scenes. Readers highlight the great tension and chemistry between the two main characters, Calla and Nash that leaves them begging for more.

The books feature great storylines with twists and turns and an alternation of action and scene setting that will keep you on the edge of your seat.

Each book in the Decrypter series can be read as a stand-alone novel, offering a fast-paced, action-packed adventure. While you can jump in anywhere, the series is best enjoyed in order to fully appreciate the character development and overarching plotlines.

The Decrypter Mission Log: Books 1‑8

# Code Name Your Adrenaline Brief
1 Secret of the Lost Manuscript A Berlin heist swipes an indecipherable WWII document. Calla must unlock its riddle before a shadow syndicate weaponises its secret.
2 Mind Hacker Kidnapped after a blast in Colorado, Calla is forced to track an MI6 agent whose knowledge could trigger a global cyber‑collapse.
3 Digital Eyes Only 10 Downing Street is breached. A single cipher is the only clue—and the countdown has started.
4 The Storm’s Eye A derelict research base on an uncharted island hides experiments that should never have resurfaced. Storms, drones, buried lies.
5 The Pythagoras Clause A viral prediction app puts civilians in comas. Ancient math, modern AI, and an old nemesis converge on London.
6 The Beale Ciphers Framed for her best friend’s murder, Calla must decode a legendary cipher to clear her name and stop a treasure‑hungry cabal.
7 Atlantis of the Sands Desert winds whisper of a lost city. To find it, Calla confronts mercenaries, myth, and an ancient malevolence older than the dunes.
8 Kingdom of Diamonds Deep in the Kalahari Desert, a sunken ship laden with priceless stones—and a weaponised secret—drags Calla back into clandestine warfare before a criminal mastermind claims the ultimate prize.

Each thriller stands alone, but read in order for an escalating tapestry of betrayals, tech fears, and personal revelations.

Why Fans Clear Their Schedule

Real history, upgraded: forgotten manuscripts, lost civilizations, and true cryptographic puzzles anchor every plot.

Tomorrow’s threats, today: quantum hacks, rogue AI, bio‑weaponised data—stakes ripped from headlines that haven’t printed yet.

A heroine who outthinks the bullets: Calla survives by being the smartest operative in the room, and sometimes the most ruthless.

Cinematic pacing: short chapters, ticking clocks, and end‑of‑act whiplash twists that make “one more chapter” impossible.

Choose Your Decryption Point

Start with Book 1 if you love origin stories, or dive into the title whose code name intrigues you most—the mission briefs ensure you’re never lost. Prefer binge reading? Grab the 7‑Book Bundle for a permanent adrenaline subscription. 

“Heart‑pounding like 24, brain‑teasing like Da Vinci Code—Calla Cress is the codebreaker heroine we’ve been waiting for.” — Reader Reviewer

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Join Calla, Nash, and Jack today for adventure that blends history, technology, and high-stakes espionage!

Crack the cipher. Stop the clock. Dive in.