Katherine Schneider’s life as a dentist in 1913 New York is upended when a patient reveals details of a deadly plot while under the influence of laughing gas. As she is plunged into danger, she seeks help from the dashing Lieutenant Jonathan Birch, a police officer she has long admired from afar.

When the backlash from her work forces a return home to Baltimore, Clara finds herself face to face with a childhood sweetheart who is no longer the impoverished factory worker she once knew. In her absence, Daniel Tremain has become a powerful industry giant and Clara finds him as enigmatic as ever. However, Daniel's success is fueled by resentment from past wounds and Clara's deeply held beliefs about God's grace force Daniel to confront his own motives.

Gray Delacroix has dedicated his life to building his very successful global spice empire, but it has come at a cost. Resolved to salvage his family before it spirals out of control, he returns to his ancestral home to save his brother and sister before it's too late. As a junior botanist for the Smithsonian, Annabelle Larkin has been charged with the impossible task of gaining access to the notoriously private Delacroix plant collection. If she fails, she will be out of a job and the family farm in Kansas will go under. 

Anna O'Brien leads a predictable and quiet life as a map librarian at the illustrious Library of Congress until she stumbles across the baffling mystery of a ship disappeared at sea. Thwarted in her attempts to uncover information, her determination outweighs her shyness and she turns to a dashing congressman for help. Luke Callahan was one of the nation's most powerful congressmen before his promising career was shadowed in scandal. Eager to share in a new cause and intrigued by the winsome librarian, he joins forces with Anna to solve the mystery of the lost ship. 

Despite her misgivings, Kate agrees to Trevor's risky proposal to join him in his work to find a cure for tuberculosis. As Kate begins to unlock the mysteries of Trevor's past, his hidden depths fascinate her. But a shadowy enemy lies in wait, and Trevor's closely guarded secrets are darker than she ever suspected. As revelations from the past threaten to destroy their careers, their dreams, and even their lives, Trevor and Kate find themselves in a painfully impossible situation. With everything to lose, they must find the strength to trust that hope and love can prevail over all.