After spending her childhood as a street thief, Gabriella Goodhue thought she'd put her past behind her until a fellow resident at her boardinghouse is unjustly accused of theft. Using her old skills to prove her friend's innocence, Gabriella unexpectedly encounters Nicholas Quinn, the man she once considered her best friend—until he abandoned her. After being taken under the wing of a professor who introduced him into society and named him as his heir, Nicholas is living far removed from his childhood life of crime. As a favor to a friend, Nicholas agreed to help clear the name of an innocent woman, never imagining he'd be reunited with the girl he thought lost to him forever. As Gabriella and Nicholas are thrown together into one intrigue after another, their childhood affection grows into more, but their newfound feelings are tested when truths about their past are revealed and danger follows their every step.

Miss Daphne Beekman is a mystery writer by day, inquiry agent by night. Known for her ability to puzzle out plots, she prefers working behind the scenes for the Bleecker Street Inquiry Agency, staying well away from danger. However, Daphne soon finds herself in the thick of an attempted murder case she's determined to solve. Mr. Herman Henderson is also a mystery writer, but unlike the dashing heroes he pens, he lives a quiet life, determined to avoid the fate of his adventurous parents, who perished on an expedition when he was a child. But when he experiences numerous attempts on his life, he seeks out the services of the eccentric Bleecker Street Inquiry Agency to uncover the culprit. All too soon, Herman finds himself stepping out of the safe haven of his world and into an adventure he never imagined. As the list of suspects grows and sinister plots are directed Daphne's way as well, Herman and Daphne must determine who they can trust and if they can risk the greatest adventure of all: love.

When a man arrives at the Bleecker Street Inquiry Agency, anxious to hire them to find a missing heiress, Eunice Holbrooke realizes her past has finally caught up with her . . . and that she may no longer be able to hide under the disguise that has kept her safe for so long. Arthur Livingston's goal in life is to make his mark on the world as a mining industrialist, but after the man who could help him achieve his goal is murdered, Arthur feels compelled to seek justice for the family—but he's left with more questions than answers after the eccentric Bleecker Street Inquiry Agency refuses to take on his case. Desperate to conceal her real identity and avoid the irritatingly handsome Arthur, Eunice takes on a different case that requires her to go deep undercover and entangles her in one troublesome situation after another. When other secrets come to light, Eunice has no choice but to confront her past, hopeful that it will set her free but knowing it could very well place her life—and the lives of those she loves—in jeopardy.