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Silver Gravity Books

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Helium Heist: The Nash Shields Thrillers, Rose Sandy, Book 1

Action & adventure, Thriller & suspense, Suspense, Technology, and Crime & mystery

Every Silver Gravity story centres women with agency.

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Power a city. Black out a continent. One stolen element could rewrite the world, and the only man who can stop it just made it personal.

Nash Shields wanted quiet. London. Embassy security. No ghosts. Instead, a late-night breach pulls him into KJ20-Ops, a unit so classified it lives beyond Umbra. Their first target: a bronze canister lifted from the British Museum, a purpose-built cradle for helium-3. If stabilised, it could power a metropolis. If weaponised, it could black out continents.

The hunt turns deadly when a thief slips through the British Museum with an artefact etched in enigmatic symbols, and brilliant curator Calla Cress becomes an unexpected ally and distraction. As Nash partners with the gravel-voiced legend Masher and the hard-to-read General Rodney Cook, breadcrumb clues point to a name that freezes his blood: Foster Shields, Nash's estranged brother, alive and entangled deep in the conspiracy.

Across rain-slick London streets, embassy sub-levels, and international dead drops, Nash closes on a ruthless architect of the plot: Mason Laskfell, a former intelligence chief weaponising science beyond current understanding. When intel points to a maritime transfer, KJ20 launches a stealth ship into a North Sea storm to intercept the Ulysses V. On a slick, howling deck, Nash cradles a glowing pod as containment cracks and bullets chase the team into the sky.

Some wars are fought for nations. This one is fought for family. Perfect for readers who love the sleek tradecraft of The Gray Man, the high-concept science of Sigma Force, and the moral complexity of Orphan X.

Featured Locations

U.S. Embassy, London - sublevel war room where power plays unfold
The British Museum - from public grandeur to dead-zone archives where history resonates
KJ20 Facility - secure data room where blue-lit telemetry reveals shifting loyalties
The Scorpion Tide - silent stealth boat cutting fog from Thames to North Sea
Cargo Ship Ulysses V - industrial labyrinth in lightning where extraction becomes crucible
Scottish Highlands - fog-blanketed training annex providing clarity in isolation

Reader Praise

"The British Museum chase had my heart in my throat. Nash and Calla crackle on the page."
"Finally, a technothriller with brains and bruises. The KJ20-Ops world is catnip for fans of The Gray Man."

About the Calla Cress Decrypter Series

The Calla Cress Decrypter Series is a female-led action-adventure techno-thriller series that blends global espionage, cryptography, and high-stakes discovery.

Often compared to a female James Bond crossed with Indiana Jones, the series follows Calla Cress, a brilliant cryptographer and museum curator whose expertise in ancient manuscripts and hidden systems draws her into international conspiracies. As intelligence agencies, criminal networks, and secret organisations collide, Calla is forced to navigate a world where knowledge is power — and decoding the truth can destabilise nations.

Each book stands alone while contributing to a larger arc of global intrigue, making the series perfect for readers who enjoy smart, fast-paced thrillers led by a woman who survives on intellect, courage, and moral clarity rather than brute force alone.

What Kind of Thriller Is This?

This book is best described as a female-led action-adventure techno-thriller.

It combines:

Technothriller elements (cryptography, data, hidden systems, modern intelligence warfare)
Espionage and conspiracy involving governments and shadow organisations
Action-adventure storytelling across global locations
A smart female protagonist whose intelligence drives the plot

If you enjoy thrillers where ideas are as dangerous as weapons — and where discovery triggers global consequences — this series is designed for you.

If You Love James Bond or Indiana Jones…

Readers often compare this series to James Bond and Indiana Jones, but with a modern, female-led twist.

Like James Bond, the story features global stakes, intelligence agencies, and dangerous conspiracies.
Like Indiana Jones, it revolves around ancient knowledge, hidden artefacts, and discoveries that reshape history.

What sets Calla Cress apart is that intelligence is the primary weapon. Codes replace gadgets. Pattern recognition replaces brute force. And the heroine’s strength lies in insight, scepticism, and resolve.

Story Tropes & Reader Appeal

Is This Book for You?

Do I Need to Read the Series in Order?

Each Calla Cress novel is written to stand alone, with its own central mystery and resolution.

However, reading the series in order allows you to follow Calla’s evolving relationships, growing influence, and the wider conspiracy arc that unfolds across the books. New readers can start here, while returning readers will uncover deeper connections.

The Calla Cress Decrypter Thriller Series In 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 Falcom Syndrome
Book 10: The Queen of Sheba
Book 11: The Calculus Warning
Book 12: The Cobra Paradox
Book 13: Room of Martyrs
Book 14: Eiger Mosaic
Book 15: Enemy of Wolves
Book 16: The Pharaoh's Mask
Book 17: The Eternity Hypothesis
Book 18: The Sculptor's Code
Book 19: The Solomon Agenda
Book 20: The Pheonix Cipher
Book 21: The Cairo Key
Book 22: Red Fox Agenda
Book 23: Phaistos Disc
Book 24: Scorpion Gold

About Rose Sandy

Rose Sandy is an independent author and publisher known for writing female-led action-adventure and techno-thriller fiction.

She is the creator of the Calla Cress Decrypter Series, a globe-spanning techno-thriller series often compared to a female James Bond crossed with Indiana Jones. Her work blends cryptography, global conspiracy, and high-stakes discovery, with a focus on intelligent heroines who survive through insight, courage, and moral clarity.

Rose Sandy’s stories are characterised by fast-paced plots, international settings, and the collision of history, technology, and power. Her fiction is written for readers who enjoy smart thrillers with real-world stakes and strong female protagonists at the centre of the action.