Groton Bank covers a small area — a half square mile — but it casts a big shadow when it comes to the ghost stories that linger around its historic sites.

At the Avery-Copp House, many folks over the years have noticed an apparition in the north-facing windows, a figure that looks female and wears clothing that’s filmy white but not transparent.

At The Subvets Club, some people have had the sensation of being touched. Others have heard noises coming from the room that used to be a theater.

At the Mother Bailey House a few years ago, two city employees inspecting the basement saw a transparent image of a man in Revolutionary War-era clothing. They even reportedly snapped a cellphone photo of it.

Hali Keeler has collected Groton Bank tales of supernatural possibilities in a new book. “Ghosts of Groton Bank,” which also features work from contributors Leslie Evans and David Rose, is published by Haunted America, a division of The History Press. It gets a book launch party at 7 p.m. Monday at the Bill Memorial Library in Groton.

The seeds for the book actually began with Groton ghost tours that have been a popular attraction around Halloween. Those tours, in turn, were inspired by a chat among history-minded Groton folks.

“There were a bunch of us from these various historic groups — I don’t remember the circumstance, but we were sitting around one day telling ghost stories,” says Keeler, who is president of the board of the Avery-Copp House.

Their reminiscing about the legends they’ve heard and the experiences people have had in historic buildings led to developing the ghost tour that debuted in 2012. The walking tours, written by Leslie Evans, became a popular Halloween-pegged event. The treks started at the Avery-Copp House and then continued to various buildings and homes where paranormal things were said to have happened.

“We were having a lot of fun with it,” Keeler says of the tours. “It was great, because people would sidle up to you when you’re walking from location to location (and say), ‘I have to tell you about an experience I had ...’ So you got all kinds of information.”

When Keeler attended the New England Independent Booksellers Association trade show in the fall of 2014, she stopped at the History Press booth and learned about its Haunted America series. She told a publishers’ rep about the ghost tours in Groton, and that eventually led to this book.

“Ghosts of Groton Bank” is as much about history as it is about ghost tales.

“If it weren’t for the fort (Fort Griswold), if it weren’t for Mother Bailey, we wouldn’t have the stories because they’re all part of history. And they’re still with us,” Keeler says.

Keeler worked at the Bill Memorial Library in Groton for 35 years before retiring as director in 2014, and she is also writing a series of library support staff handbooks for Rowman & Littlefield publishers. (“Ghosts of Groton Bank” contributor Evans is director of the Avery-Copp House, and Rose is a former president of the Friends of Fort Griswold and is retired from her post as registrar of voters in Groton and from a position at Pfizer.)

Keeler says that people often used to ask her if the Bill Memorial Library was haunted. She will say this much: there have been many times where things “sort of appeared out of nowhere.”

A prime example: after a film crew shot scenes for the 1994 James Woods movie “Killer: A Journal of Murder” at the library, Keeler found on a bookcase an 18th-century document conscripting a man into the military and featuring the seal of Colonel William Ledyard.

“We’d never seen that document before,” she says. “It was the first I ever saw it, and if the previous librarians years ago knew about it — maybe they stuck it between the pages of a book and put it away and it fell out — I don’t know. I’m not ruling anything out. But that’s a pretty important piece of paperwork. And it was just lying there.”

On another occasion, a contractor replacing the library boiler had his tools go missing ... and then mysteriously reappear. When things went missing, the library staff members would, though, joke that “Mr. Bill” was the culprit. For years, too, the people who work there have noticed the smell of pipe smoke.

Two years ago, the library invited the Thames Society of Paranormal Investigations to run its studies on the site. They concluded that, yes, it’s spiritually active, with the activity “most likely connected to an unknown male that is present on the 2nd floor.” The Thames Society of Paranormal Investigations went into the Avery-Copp and Mother Bailey houses as well.

Asked whether she personally believes in ghosts, Keeler says, “We don’t know everything, so I’m not going to say it’s not possible. I’ve had experiences in my own homes, but I’m not sensitive (to the paranormal). I couldn’t tell you there’s something behind your shoulder. I couldn’t walk into a house and feel something’s going on. But I know that the house I live in now is the only place I’ve felt truly comfortable.”

In the book’s introduction, Keeler recounts how, for instance, when she lived in a house in the woods, some lights went on and alarms went off in the middle of the night. She and her daughter both heard voices there. Keeler once came home to find the contents of a kitchen cabinet shelf arranged in a row on the counter.

In short, Keeler says, “We can’t know everything. I’m keeping an open mind.”

By the book

What: “Ghosts of Groton Bank”

By: Hali Keeler with Leslie Evans and David Rose

List price: $19.99

Publisher: Haunted America, a division of The History Press

Available at: Locations include Bank Square Books, Mystic, and Books-a-Million, Waterford.

Funds raised: Royalties from the sale of the book will be dedicated to the future restoration of the Amos Prentice House on Thames Street, also known as the Mother Bailey House. 

IF YOU GO

What: Book launch party

When: 7 p.m. Monday

Where: Bill Memorial Library, 240 Monument St., Groton

Register at: (860) 445-0392

Other book signings:

Oct. 8, 1-3 p.m., Books-a-Million, Waterford; Oct. 16, 2-4 p.m., Groton Public Library; Oct. 23: 1-3 p.m., Bank Square Books, Mystic; Oct. 28: 6-8 p.m., program and signing at Avery-Copp House Museum, Groton