When family secrets collide with international espionage, three brilliant girls must protect a legacy that could change humanity's future forever. Hidden ciphers in her grandfather's desk reveal that Sam McAllister wasn't just a quiet professor, he was the secret sixth member of HELIOS, a legendary space technology project that everyone believed was lost to history. But HELIOS isn't just about energy systems. It's a complete framework for sustainable human civilization beyond Earth, and whoever controls it will shape humanity's expansion into space. As shadowy figures keep surveilling the family and her mother's NASA mission faces deliberate sabotage, Attie realizes they're caught in an international conspiracy decades in the making. With her best friends Raye and Jenny, she must decode her grandfather's encrypted legacy while dodging surveillance, protecting classified research, and discovering that everything she thought she knew about her family was carefully orchestrated preparation for this moment. From Rocket City's aerospace corridors to a Scottish manor hiding centuries of secrets, the girls navigate corporate espionage, federal investigations, and the revelation that Sam McAllister spent his entire life preparing the next generation to complete what he started. But as secrets come to light and former allies reveal their true loyalties, Attie faces an impossible choice: protect her family's safety or preserve a legacy that could determine humanity's future among the stars. Legacy isn't just what you inherit—it's what you're willing to fight to protect. Life Skill Focus : Life Planning & Legacy Foreword By: Julia Taylor Meet the Series That’s Inspiring Girls Everywhere! Book Order 1 Rocket City Love – Every inventor’s story starts with a spark. 2 Tick Tock, Take Charge! – Adventure doesn’t come with a pause button. 3 Where Clues Take Root – Decode the past. Protect the future. 4 Blueprints & Buried Truths – From hidden ciphers to hydrogen power, the secrets of HELIOS rise. 5 Calculated Risks – The formula for courage: friendship + truth + risk. 6 The Gravity of Choice – Decisions have gravity. Attie’s could shift the future. 7 Legacy Protocol – HELIOS was never lost—it was waiting for her. Download & Learn by Doing — Just Like Attie Each book includes a download (available at the Charms Book Series website) to help readers apply Attie’s real-world life skills: time management, pitching, project management and more. Learn by doing and see how STEM and storytelling connect! Your Purchase Makes a Difference By purchasing this book—or any Charms merchandise—you’re supporting Athenian, a STEM edu-tainment nonprofit dedicated to empowering girls through hands-on learning, storytelling, and real-world adventure. Every Charms purchase fuels our mission to build confidence, character, and curiosity in next gen innovators. Together, we’re shaping the future—one story at a time. If you like Tree House Mysteries, The Baby-Sitters Club, Nancy Drew, Carole Marsh’s mystery books, National Park Mystery Series, The Math Inspector series, then the Charms Book Series is the natural next step. Those favorites deliver friendship, adventure, and curiosity and Charms keeps that same feel while leveling up for ages 8–14 (grades 6–9) with older characters, deeper thinking, and real problem-solving. This juvenile fiction / middle grade chapter book series for girls blends mystery and STEM-ready curiosity with life skills like decision-making, confidence, responsibility, and leadership making it perfect for reluctant readers, libraries, book clubs, and parents who want fun, safe stories that quietly strengthen literacy. Still funny. Still wholesome. Just a little more “you’ve got this” and a lot less hand-holding.