The Mine By John Heldt

Summary By Goodreads:
In May 2000, Joel Smith is a cocky, adventurous young man who sees the world as his playground. But when the college senior, days from graduation, enters an abandoned Montana mine, he discovers the price of reckless curiosity. He emerges in May 1941 with a cell phone he can't use, money he can't spend, and little but his wits to guide his way. Stuck in the age of swing dancing and a peacetime draft, Joel begins a new life as the nation drifts toward war. With the help of his 21-year-old trailblazing grandmother and her friends, he finds his place in a world he knew only from movies and books. But when an opportunity comes to return to the present, Joel must decide whether to leave his new love in the past or choose a course that will alter their lives forever. THE MINE follows a humbled man through a critical time in history as he adjusts to new surroundings and wrestles with the knowledge of things to come.

The Old Man And The Princess by Sean-Paul Thomas

Summary By Goodreads:

An eccentric old Irish man, who claims to be 'not of this Earth,' kidnaps Sersha, a young, headstrong, Irish girl, from the streets of Galway and tries to convince her that her life's destiny is tied to a mystical cave in the Scottish highlands.

But with half of the Irish criminal underworld violently on their trail, Sersha, struggles back and forth with the old man's real identity and far fetched intentions to whether he truly is genuine in his wild and fantastical beliefs. Or is he really just a mad, demented, old fool, having some kind of mental breakdown in his twilight years. 

Indiana Belle By John A. Heldt

Summary By Goodreads:
Providence, Rhode Island, 2017. When doctoral student Cameron Coelho, 28, opens a package from Indiana, he finds more than private papers that will help him with his dissertation. He finds a photograph of a beautiful society editor murdered in 1925 and clues to a century-old mystery. Within days, he meets Geoffrey Bell, the "time-travel professor," and begins an unlikely journey through the Roaring Twenties. Filled with history, romance, and intrigue, INDIANA BELLE follows a lonely soul on the adventure of a lifetime as he searches for love and answers in the age of Prohibition, flappers, and jazz.