"A Soldier's Secret" is a historical fiction novel by Marissa Moss, published in 2019. The story is set during the American Civil War and follows the journey of Sarah Emma Edmonds, a young woman who disguises herself as a man named Frank Thompson to join the Union Army and fight for her country. As Frank, Sarah experiences the harsh realities of war, facing challenges, camaraderie, and the horrors of battle. Along the way, Sarah must carefully guard her true identity while forming deep connections with her fellow soldiers, including a budding romance. However, as Sarah's service continues, her secret becomes increasingly difficult to maintain, and she must confront the consequences of her deception. "A Soldier's Secret" is a compelling tale of courage, sacrifice, and the search for identity, shedding light on the challenges faced by women who disguised themselves as men to fight in a male-dominated world during a tumultuous period in American history.