The University of Manitoba in Winnipeg, Canada.

The story he heard about a sniper didn’t make sense.

How could it be that in the cold Canadian winter, a woman would go to the porch to breastfeed her child, and be shot in a random drive-by at a time when cars were not common.

This is what Wayne Hoffman, executive editor of Tablet, and a novelist, wondered for many years. It was the story that his mother told him. After talking it over with his staffers, he went on a quest to find out what really happened to his great-grandmother, Sarah Feinstein.

In his sensational book, “The End of Her: Racing Against Alzheimer’s To Solve A Murder” (Heliotrope), Hoffman writes of his search for the truth, while at the same time dealing with his mother’s dwindling health. We learn that his mother Susan suffers from Minear’s Disease and Alzheimer’s Disease, and he is in a race against the clock to find the true identity of the murderer and tell his mother while she could still understand and retain it.

He discovered that Sarah Feinstein was actually shot indoors, while sleeping in her bed, on Friday, August 1, 1913. One child was next to her and another was nearby. Her husband, David, was away on a business trip. But who would shoot a homemaker point blank in the head as she slept? With no talk of affairs or major feuds, what motive could there be? Surely, as one of only six murders in the area for the year, police would solve the case, right? Wrong.

There would be arrests, suspects, and appearances in court, but it ended up becoming a cold case.

It was said that Sarah fired a 24-year-old Galician woman named Mary. Could she have done it? What about Stefan, a man who seemed to be her suitor? There was also a servant named Victoria. What of the dark rumors of a secret society from Russia? How was it that the door was unlocked when it was usually locked? Could the murderer have had a key? Was it a jilted lover from Russia who declared he would get revenge even if it took a lifetime? As implausible as it would seem, could David have hired a hitman to do it and make sure he was gone at the time of the tragedy?  And what of the talk of a young man scratching at the window, or a man named Abram Schurman, who likely lied to the authorities?

Police and journalists who came to 520 Magnus Avenue had difficulty investigating the case, because they did not speak Yiddish, which the Jewish residents mainly did. Meticulous in telling his tale, Hoffman includes that the Torah portion read the day after the murder, “Masei,” included the rule that a murderer should be put to death.

The police determined that robbery didn’t seem to be the motive, as valuables could have been taken, but were not. And if the murderer was an antisemite, that certainly would not have narrowed down the list of suspects.

There are moments of humor in the book, such as when his mother, well before her mental decline, worked for a nutrition program and made large amounts of tuna salad. The diamond of her engagement ring fell off and she suspected it fell into the fish that was served. There’s a whole lot of love in the book for his mother. I teared up at the part where she shows confusion, packs a bag, and says she wants to go home, because I remember my grandmother, Minnie, doing the same. She too suffered from Alzheimer’s Disease, and would also ask for her mother, even though she died many years before.

The murder was a major story not only locally, but nationally in Canada, and 3,000 people came to the funeral. In combing through different newspaper accounts from that time, Hoffman notes that it was difficult to distinguish between fact and rumor, and there were numerous inconsistencies.

The book contains a second mystery. Could Fanny, a daughter of Sarah, have been given away a few years after the murder? Or could she have been one of those who died as a result of the influenza pandemic that began in late 1918?

I’d be shocked if this book wasn’t made into a movie, as it would appear that Hoffman has solved both mysteries. If you’re heading to the beach in the last days of summer, this is the book to take along and read. Jam-packed with suspense, emotional power, and a sense that there are few greater calls of duty than the one a son has to help his mother, it’s one of the best books of the year.

The author is a writer based in New York.