The explosion of a Canadian Pacific Airlines flight over Quebec's Charlevoix region on September 9, 1949, shocked the province.

Twenty-three people travelling to Baie-Comeau, Que., died that day, including Rita Morel, the mother of a four-year-old girl.

Morel's husband, Albert Guay, was later hanged for his role in one of the first bombings on a passenger plane in Canada.

But Guay hadn't acted alone.

And the plan he put into place to kill his wife would inspire one of Quebec's most renowned writers, Roger Lemelin, to write his book Le crime d'Ovide Plouffe, later adapted as a feature film by director Denys Arcand.

Radio-Canada's Catherine Lachaussée's sifted through news articles from that period, as well as history books written about the tragedy, before returning to the site of the crash, near the St. Lawrence River, 70 years after the fatal crash.

Sept. 9, 1949

On the morning of September 9, the DC-3 left Montreal around 11 a.m., stopping briefly in Quebec City to pick up more passengers and some parcels.

Sixty-five kilometres after lift-off, "a crash of thunder" was heard over the Charlevoix coastline, near Petite-Rivière-Saint-François.

Fisherman Patrick Simard lifted his eyes to the sky, later describing to a reporter with Le Soleil that it was like "the plane had been hit" by an object.

The crash site of the 1949 Canadian Pacific Airlines flight is still sprawled out on the forest floor, between Saint-Tite-des-Caps and Petite-Rivière-Saint-François, east of Quebec City. (Catherine Lachaussée/Radio-Canada)

The aircraft quickly lost altitude before disappearing behind the steep mountains.

At nightfall, guided by torch lights, investigators with Canadian Pacific Airlines found the plane.

No one had survived.

The crash site, in a remote forested area called Sault-au-Cochon, was later described as "intolerable".

Bodies lay on the ground near the metallic carcass of the airplane, that hadn't burst into flames upon impact.

The propellers were twisted — an indication they continued to spin until the moment of impact, throwing out the theory of a mechanical malfunction.

The relative good condition of the plane would later prove crucial to the investigation, allowing RCMP, provincial and Quebec City police forces to determine exactly where the bomb had exploded.

Mysterious package

The baggage compartment on the left side of the plane, torn to pieces, contained items that had been picked up in Quebec City shortly before the crash.

The log book indicated one person who had dropped off a parcel at the last minute had given a fake address.

Testimony from an airport employee led police to look for a "tall woman, dressed in black" who had arrived in a taxi.

The taxi driver later described his client as an "elegant" woman who was holding a package with the word "Fragile."

Marguerite Pitre lived in Quebec City's Saint-Roch neighbourhood and was nicknamed 'the raven' by locals, because she was always dressed in black. (BANQ/GETTY IMAGES)

During the ride, she had repeatedly told the driver to be careful and not to speed.

The story of the mysterious woman would eventually be published by a reporter in Le Canada, before police were able to identify the suspect.

Marguerite Pitre, was nicknamed le corbeau, the raven, by locals in the Saint-Roch neighbourhood because she always wore black.

Realizing she was the main suspect in such a horrible crime, she became suicidal — considered a criminal offence in Canada until 1972.

Pitre woke up in hospital one day after attempting to take her own life. Police interrogated her there.

That's when she admitted she had delivered a package to the airport the day the plane exploded. Pitre always maintained her innocence however, claiming she thought she was delivering a statue of the Virgin Mary.

Her testimony pointed police toward Albert Guay, and Pitre's own brother, Généreux Ruest.

The clockmaker

Pitre knew Guay, because she had allowed his mistress, 19-year-old Marie-Ange Robitaille to live with her.

Guay was willing to risk everything to marry Robitaille.

That's when he put his plan into motion to murder his wife, Rita Morel, who had found out about the affair.

Guay was a jeweller and asked Morel to travel to Baie-Comeau to drop off an order for a customer. After purchasing the ticket, Guay also took out a $10,000 life insurance.

He then turned to a clockmaker he knew in Saint-Roch. Généreux Ruest used his skills to make a detonator, timed to explode at the exact moment the plane would be flying over the St. Lawrence River, toward the North Shore.

Albert Guay planned the attack to get rid of his wife, Rita Morel, centre, in the hopes of marrying Marie-Ange Robitaille. (Bibliothèque et Archives Nationales du Québec)

Had the plane sunk to the bottom St. Lawrence, investigators would have lost crucial pieces of evidence.

But the DC-3 took off five minutes late — and was flying over the coastline when it plunged down and crashed, killing the 23 people on board.

In 1953, all three would be sentenced to death in three separate trials.

Pitre was hanged on January 9, and was the last woman to be executed in Canada.

Piece of the past

What is left of the aircraft remains tucked away in a remote area of the lush forest, near Petite-Rivière-Saint-François, 150 metres above the level of the St. Lawrence River.

Despite its remote access, which requires an all-terrain vehicle to cover several kilometres of logging trails, some people have visited the site and taken off with parts of the aircraft, according to local guide Carol Duclos.

That fascination with the tragic story also inspired Roger Lemelin as he was writing Le crime d'Ovide Plouffe, even though the storyline was quite different than the real-life events.

The lettering on the aircraft is still visible on the few aluminum panels left at the crash site. (Catherine Lachaussée/Radio-Canada)

Lemelin also reported on the trial and happened to know all three characters personally, from his time living in Quebec City's lower town.

In a 1951 publication in Maclean's, titled, My Friend Guay, the Murderer, Lemelin described how he knew Guay had to be involved the moment he heard Rita Morel was among the victims.

"And, incredible as it may seem looking back, my second reaction was: 'Albert had something to do with that explosion.'"