Book ~ "Class of '59" (2016) John A. Heldt

From Goodreads ~ When Mary Beth McIntire settles into a vacation house on June 2, 2017, she anticipates a quiet morning with coffee. Then she hears a noise, peers out a window, and spots a man in 1950s attire standing in the backyard. She panics when the trespasser sees her and enters the house though a door to the basement. She questions her sanity when she cannot find him.

In the same house on March 21, 1959, Mark Ryan finds a letter. Written by the mansion’s original owner in 1900, the letter describes a basement chamber, mysterious crystals, and a formula for time travel. Driven by curiosity, Mark tests the formula twice. On his second trip to 2017, he encounters a beautiful stranger. He meets the woman in the window.

Within hours, Mary Beth and Mark share their secret with her sister and his brother and begin a journey that takes them from the present day to the age of sock hops, drive-ins, and jukeboxes.

It's 2017 and Mary Beth is recovering from the death of her fiancé, Jordan, almost a year ago.  She is on vacation with her family and staying in the house of her father's friend in California.  One morning she sees a man coming and going from the house.  When she goes to confront him, he has disappeared.

It's 1959 for Mark Ryan and he and his family have just moved into a house.  One day he discovers a tunnel that takes him to 2017.  He goes twice, the second time being confronted by Mary Beth.  She is quickly comfortable with him and believes him.

Mary Beth and Piper, her younger sister, are looking for an adventure so go back to 1959 with him for a couple weeks.  Piper becomes friends with Mark's younger brother, Ben.  As the two couples become closer, they have a difficult decision to make ... do Mary Beth and Piper stay in 1959, do Mark and Ben go to and stay in 2017, or do the two couples break up and stay in the own years?

This is the eighth book I've read by this author and I liked it.  I like time travel books when people go back in time where there are no cell phones, no Internet, etc.  Though it is the fourth in the American Journey series, you don't have to read the others since these characters aren't in the other books.  The author wrote about 1959 well and I got a good sense of what it was like living in that time period ... it was such a polite time.  It is written in third person perspective.