Willow finds herself drawn to the hotel's new busboy, Graham, but little does she know he's a railroad heir working undercover to track down criminals using his trains. As he sets out to find the truth, another truth soon becomes equally urgent—will the Harvey Girl he has come to love care for the railroad heir as much as she cared for the lowly busboy?

Calista York needs one more successful case as a Pinkerton operative to secure her job. When she's assigned to find the kidnapped daughter of a mob boss, she's sent to the rowdy mining town of Joplin, Missouri, despite having extended family in the area. Will their meddling expose her mission and keep Lila Seaton from being recovered? When Matthew Cook decided to be a missionary, he never expected to be sent only a short train ride away. While fighting against corruption of all sorts, Matthew hears of a baby raffle being held to raise funds for a children's home. He'll do what he can to stop it, but he also wants to stop the reckless Miss York, whose bad judgment consistently seems to be putting her in harm's way. Calista doesn't need the handsome pastor interfering with her investigation, and she can't let her disguise slip. Her job and the life of a young lady depend on keeping Matthew in the dark.

Maisie Kentworth is stuck on the ranch. Having fallen in love with the wrong guy, she can't risk inflaming things between her former beau and her protective family. Left to rue her mistakes, she keeps busy exploring the idle mine at the edge of their property. Boone Bragg is also stuck. With his parents on vacation, the management of Bragg Mining falls on him, and one of his advisors wants him as a son-in-law. One wrong move, and Boone will end up either offending an associate or getting married to a woman he can't endure. While closing up a spent mine, Boone gets two surprises. One is an untamed farm girl who's trespassing with a pickax, and the other is the amazing crystal cavern that she's discovered. Suddenly Boone sees a way to overhaul the family business. With part of the cavern on Kentworth land, Boone makes Maisie a proposal that he hopes will solve all of their problems. Instead it throws Joplin into chaos.

Olive Kentworth has spent her life hiding her interest in architecture, even though she pores over architectural books and sketches buildings. When she accepts a job on a home expansion, it's only because her cousin Amos agrees to pose as the builder. To further hide her involvement, Olive takes a position as a nanny—not knowing that she'll be working for her idol, Joplin's leading architect, widower Maxfield Scott. Maxfield is intrigued by his new nanny—she makes his home and his life bearable again. His work, on the other hand, is a disaster. An untrained builder is remodeling a completed project of his. What's worse, Maxfield's current client wants changes to his plans because of that builder's work. As the architectural one-upmanship heats up, Olive's involvement becomes harder to hide. Will the relationship between her and Maxfield survive, or will they both miss out on building something for their future?