Thriller & suspense, Travel, Technology, History, Action & adventure, Crime & mystery, and Suspense
Every Silver Gravity story centres women with agency.
Six Cryptic Codes. One Fearless Heroine. Infinite Danger.
If you love globe-trotting thrillers packed with ancient mysteries, high-stakes espionage, and a brilliant heroine who outsmarts everyone in the room, this is the bundle you have been waiting for.
Books 13 through 18 in the internationally bestselling Calla Cress Decrypter Thriller Series by Rose Sandy, collected in one unmissable ebook bundle. Calla Cress, British Museum curator, elite codebreaker, and covert ISTF operative, faces her most personal and world-altering missions yet across six consecutive adventures.
Book 13: The Room of Martyrs
When a Vatican archivist vanishes after discovering a hidden chamber beneath St. Peter's Basilica, Calla Cress is summoned to Rome. Inside the forbidden vault lie ancient relics and coded diaries holding a devastating secret: the martyrs' blood carries the power to control belief itself. As Calla deciphers the ancient cryptograms, she experiences vivid visions connecting her to the martyrs' final moments, a genetic ability that makes her uniquely qualified to understand the threat and dangerously vulnerable to its influence. With a global religious summit in the crosshairs and a technological genius poised to weaponise faith on a mass scale, Calla must stop the most insidious mind control weapon ever conceived.
Locations: Vatican Secret Archives, Rome, ancient catacombs, British Museum London
Book 14: The Eiger Mosaic
When satellite images reveal a mysterious mosaic carved into the treacherous north face of the Eiger, Calla recognises what others cannot: a complex cipher hidden in plain sight for over seventy years. The Alpine Cipher, a legendary WWII encryption key thought lost forever, is resurfacing alongside technology decades ahead of its time. With a catastrophic winter storm approaching and mercenaries closing in, Calla must conquer her fear of heights and scale the Eiger's deadly north face to reach the truth first. What her parents died protecting, she must now find. What others would kill to possess, she alone can decode.
Locations: Swiss Alps, Eiger north face, hidden WWII bunkers beneath the ice
Book 15: Enemy of Wolves
When digital wolves appear in augmented reality apps worldwide and infrastructure crumbles in their wake, Calla recognises something impossible embedded in the attack: ancient Nordic runes controlling modern networks. As global cities plunge into chaos, she traces the threat to a radical eco-terrorist group whose charismatic leader believes she has found the path to restoring natural balance by dismantling technological civilisation. But a darker mind manipulates the cause from behind prison walls, and when a chilling message arrives about Calla's unborn child, the mission becomes devastatingly personal.
Locations: Global cities, Arctic wilderness, ancient subglacial facility
Book 16: The Pharaoh's Mask
Beneath the sands of Egypt lies a technology that could rip continents apart. When a golden mask from a forgotten pharaoh's tomb reveals advanced engravings and awakens an ancient seismic network, Calla becomes humanity's last line of defence. Pursued across the Mediterranean by a ruthless collector and a shadowy operative, she must decode hidden inscriptions, and confront truths about her own heritage, before a precision earthquake weapon destroys millions.
Locations: Cairo Museum, Western Desert of Egypt, Vatican Secret Archives, Basilica Cistern Istanbul, Santorini Caldera, ISTF HQ London, British Museum
Book 17: The Eternity Hypothesis
Digital immortality is possible. She knows why it is forbidden. When Calla identifies an ancient pattern hidden in Tibetan manuscripts, she unwittingly becomes the key to unlocking humanity's most dangerous discovery. A secretive coalition led by billionaire tech visionary Tashi Montaigne claims to have perfected a formula merging quantum computing with ancient consciousness transfer rituals. But Calla recognises something the scientists missed: these are not just formulas. They are warnings.
Locations: Windswept monasteries of Tibet, shadowy tombs of Egypt, mysterious monoliths of Easter Island
Book 18: The Sculptor's Code
When mysterious sculptures appear in major cities worldwide, Calla must decode their ancient symbols before they trigger a digital apocalypse, one targeting anyone with her genetic markers. The statues' intricate carvings form an ancient code that activates when photographed, unleashing a Trojan horse threatening to collapse global infrastructure. The conspiracy stretches back to Renaissance Italy, where Calla's ancestors once served as secret code guardians.
Locations: The ruins of Petra, neon-lit streets of Tokyo
Fans of this series love:
- Race against time
- Ancient secrets with modern consequences
- Globe-trotting adventure across iconic locations
- Ciphers, puzzles and codebreaking
- Secret societies and shadowy enemies
- High-tech espionage meets historical conspiracy
- An unstoppable, brilliant heroine
- Betrayal, found family and reluctant allies
- World-at-stake stakes
Perfect for readers who love:
Dan Brown, Steve Berry, James Rollins, Matthew Reilly, Wilbur Smith, female-led action thrillers, archaeological mystery, techno-thriller
Bundle and Save, get all six ebooks in one purchase and dive straight into the next chapter of Calla's world. No waiting. No gaps. Just pure, unputdownable thriller fiction.
Add to cart and start reading today.
For the physical book bundles, check the Bundles drop-down menu.
