Silver Gravity Books

The Decrypter and the Calculus Warning:The Calla Cress Decrypter Thriller Series, Book 11 - Rose Sandy

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Suspense, Thriller & suspense, Action & adventure, Technology, History, Arts, Business, Crime & mystery, Family, Fantasy, Horror, Sci-fi, Travel, Western, and Romance

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Some equations were never meant to be solved.

When cryptic mathematical formulas begin appearing on government networks worldwide, decrypter Calla Cress recognizes a pattern that shouldn't exist, an 18th-century mathematical formula that perfectly predicts modern disasters. As rivers across Europe rise in perfect synchronicity, financial markets fluctuate with impossible precision, and weather systems align with mathematical certainty, one truth becomes clear: someone has unlocked "The Calculus."

Stolen from a British library's restricted section, the centuries-old manuscript contains a revolutionary mathematical framework that doesn't just predict catastrophes—it forecasts exactly how humanity will respond. In the wrong hands, it's the ultimate manipulation tool.

Racing against cascading global crises, Calla and her team—tech genius Jack, quantum computing expert Nash, and intelligence officer Marrees—must piece together the fragmented formula before reclusive data scientist Leonora Crisp can sell the complete predictions to the highest bidders. But with each solved equation, Calla discovers something even more disturbing: her own genetic connection to the mathematician who created The Calculus centuries ago.

As her cryptographic abilities evolve into something beyond explanation, Calla faces an impossible question: If mathematics can perfectly predict the future, does free will exist at all? And what does The Calculus reveal about the child she may one day have—referred to in the manuscript as "the perfect derivative"?

From the rain-slicked streets of Paris to the secure vaults of Zürich and the hidden archives of Munich, Calla must embrace her legacy as guardian of a mathematical secret that could save the world, or condemn it to a perfectly calculated destruction.

The Calculus Warning delivers heart-pounding suspense at the intersection of cutting-edge technology and ancient knowledge, where numbers don't just describe our world, they control it.

Listen to the series here:

ABOUT THE SERIES

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.

SERIES READING ORDER

The Calla Cress Decrypter Thriller Series Reading Order

Book 1: Secret of the Lost Manuscript

Book 2: The Mind Hacker

Book 3: Digital Eyes Only

Book 4: The Storm's Eye

Book 5: The Pythagoras Clause

Book 6: The Beale Ciphers

Book 7: Atlantis of the Sands

Book 8: Kingdom of Diamonds

Book 9: The Falcon Syndrome

Book 10: The Queen of Sheba

Book 11: The Calculus Warning

Book 12: The Cobra Paradox

Book 13: The Room Of Martyrs

Book 14: The Eiger Mosaic

Book 15: Enemy of Wolves

Book 16: The Pharaoh's Mask

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Meet the Author

Meet the Author Rose Sandy

Rose Sandy writes adventure thrillers that blend espionage, technology, and history into fast-paced adventures. Her stories dive into the world of covert intelligence, scientific breakthroughs, and global conspiracies, perfect for readers who love suspense with a twist of "what if?" Whether you're on a morning commute or relaxing on a Sunday, her books promise to entertain, surprise, and transport you to hidden corners of the world.

A true globetrotter and lifelong communicator, Rose draws inspiration from historical archives, cutting-edge tech, and conversations with intelligence insiders. When she's not researching in the British Library or exploring Churchill’s War Rooms, she’s crafting thrillers that weave intrigue, action, and a hint of romance.

Discover more here or join her newsletter at subscribepage.io/Wuqko4.