An author event tomorrow, Sunday, March 16, in Erving will explore the process of creating historical fiction from historical fact. Novelist J.A. McIntosh will also discuss the creation of the Quabbin Reservoir.

Few European Americans have experienced the kind of dislocation that Indigenous people underwent routinely on this continent throughout our history. One of the exceptions to that pattern took place right in our backyard: the building of the reservoir.

Four towns in the Swift River Valley — Dana, Enfield, Greenwich, and Prescott — were unincorporated in 1938 in order to flood the area. The flooding created a large body of water, which provided (and still provides) the growing population of the Boston area with drinking water.

The flooded towns and the fates of the 2,500 or so residents who were forced to move are remembered and celebrated at the Swift River Historical Society in New Salem.

That society, and the overall sense of loss in the area, form the backdrop of “Swift River Secrets” (Stillwater River Publications). Author J.A. McIntosh, who lives in Athol, is the president of the society.

Her modern-day mystery novel centers around the Historical Society’s archivist, Emma Wetherby. (Emma and the other characters are fictional.) The book opens on a blustery, muddy April day as Emma arrives at the society’s headquarters to meet with one of her co-workers, Grace Connelly.

The museum is closed for the season, but Emma wants to talk to Grace about some missing items from the collection. Unfortunately, Grace is unable to talk. She has been murdered.

In the weeks that follow, Emma turns sleuth to learn more about Grace’s past and that of the Swift River Valley. She uses her historical training, her empathy, and her instinct to track down the killer.

Her life and her search are complicated by her relationships with her romantic partner, the local chief of police, and her estranged sister, who returns suddenly to Emma’s life.

The 39-year-old Emma is both delighted and worried by her own pregnancy with a baby who may turn out to have Down syndrome.

Sprinkled throughout the book are letters and other documents that illuminate the history of Grace’s family. In many ways, its members seem never to have recovered from their ejection from their original home in the valley.

I’m a mystery fan, and I enjoyed “Swift River Secrets” greatly. McIntosh uses her historical knowledge with skill. She also creates characters that ring true. As I read, I found myself arguing mentally with Emma about her life choices. In short, I was invested in this heroine and her quest for the truth.

I also became more interested in the history of the Swift River Valley. When its Historical Society opens again in June, I hope to visit. I won’t meet Emma Wetherby, of course, but I hope to encounter some of her real-life counterparts and to learn more about the past of an important part of our state.

J.A. McIntosh will talk about writing “Swift River Secrets” and read from the book tomorrow at 2 p.m. at the Erving Public Library on Care Drive in Erving. Copies of this and of her other books will be available for sale after the event.

McIntosh’s appearance comes courtesy of the Friends of the Library. Pre-registration is appreciated but not required. To reserve a seat, call the library at 413-423-3348.

Would-be mystery writers may also be interested in another upcoming event McIntosh is helping to organize. On Sunday, May 3, she will participate in the Mystery Mansion Retreat, a day of writing and networking for mystery writers at the historic (and purportedly haunted) Wheeler Mansion in Orange.

The retreat is sponsored by Sisters in Crime New England. For more information, go to https://tinyurl.com/c8ztatnj.

Tinky Weisblat is an award-winning author and singer known as the Diva of Deliciousness. Visit her website, TinkyCooks.com.