The Charlemagne Pursuit by Steve Berry

In this gripping thriller, former Justice Department operative Cotton Malone embarks on a perilous quest to uncover the truth behind his father's mysterious disappearance during a secret submarine mission in Antarctica decades ago. As Malone delves deeper into the enigma, he unravels a web of ancient secrets tied to the legendary Emperor Charlemagne, leading him across continents and into the heart of a deadly conspiracy. With time running out and powerful adversaries closing in, Malone must navigate a treacherous path filled with historical intrigue and modern-day danger to solve a mystery that could alter the course of history.