THE THIRD KEY is an adventure novel centered around historical mysteries and ancient legends. The story follows Jack Carter and Ellie Winters as they discover a mysterious chest at the Winchester Museum that requires three keys to open. As they gradually unravel the secrets behind the chest, a complex story of revenge and historical truth gradually emerges. They not only have to face the tracking and threats from the mysterious organization "Black Key Society", but also deal with the challenges of various organs and guardians. In the process of searching for the key, they unveil the last wish of 18th century artisan Augustus Lockwood and a shocking secret that could turn the times upside down. In the end, Jack and Ellie unravel all the mysteries in a battle with destiny, preventing a catastrophe that could change history, while discovering their true calling - to become the guardians of history.