The Tide of Time. An Experienced Goods Detective Squad Mystery, #3

While old familiar classmates search for clues of the whereabouts of a former female classmate who went missing before senior prom in 1970, John introduces spectators to the old locomotive parked in front of the Minnehaha Depot in Minneapolis. The missing person, Vicky, is someone John dated in high school but now it's 2020 and he has other matters on his mind like caring for his teenage grandson and supporting his daughter as she moves back home to stay.
Meanwhile, high school students host competitions about building steam engines from scratch and displaying the models near the locomotive. The mother of the missing girl, Diane, was once a Donut Dolly. The woodworking class also refurbishes the depot to its glory days.