"Ireland's Madeleine McCann." Inside the disappearance of six-year-old Irish girl Mary Boyle.

It’s the case that’s been dubbed Ireland’s Madeleine McCann.

On March 18, 1977, Mary Boyle vanished from her grandparents’ remote dairy farm in County Donegal.

The Birmingham-born girl, who was visiting her elderly relatives for the St Patrick’s Day holiday, was just six years old.

To date, Mary remains the youngest child to ever go missing in Ireland.

Four decades on from Mary’s disappearance, no body has ever been found.

Watch the trailer for True Crime Conversations, Mamamia’s true crime podcast, below. Post continues after video.

Mary disappeared from her maternal grandparents’ house while playing outside with her siblings, older brother Paddy and her identical twin sister Ann, and her two cousins.

It’s believed that while playing outside, Mary followed her Uncle Gerry who was returning a ladder he borrowed from a neighbouring farm.

At some point on the way to the neighbour’s house, which crossed through bogland, Mary turned around to walk back to the house.

The walk back to the house should not have taken Mary more than five minutes. But she was never seen again.

While washing dishes inside the house, Mary’s mother, Ann Boyle, was told to check on the children by her father.

“‘They’re fine’, I said, ‘I can hear them playing,'” Ann told new BBC true crime podcast, No Body Recovered.

“But he said it a second time and I said, ‘I will look out.’ I went to the window and I couldn’t see the kids,” she recalled.

“I went as far as the door and I could only see a couple of them. I went over then as far as the gate and I said, ‘Where’s Mary?’ The other four children were there and they said they hadn’t seen her since dinner time.

“I panicked right away because [she] didn’t know the area.”

I haven’t said this enough but the new documentary about Mary Boyle is essential listening.

It’s heartbreaking and the family deserve justice. The government has to do something.

Please spread the word.
https://t.co/8vCLUsuuvw

— Bryan Wall (@Bryan_Wall) December 2, 2019

In the hours that followed, Mary’s family frantically searched for her.

As they were on a remote farm, the family had to attract a group of fishermen nearby the farm to ask them to alert police in the nearby town of Ballyshannon.

Speaking to BBC, a fisherman who was there on that day, PJ Coughlan, recalled those first frantic hours.

“There was panic, surely,” he said.

“With a wee girl missing on the mountain. They were all roaring and shouting ‘Mary, Mary’ – we could hear them for maybe 10 minutes before we could see them.”

As it was feared that Mary may have fallen into harsh bogland, a lake behind the cottage was completely drained and sections of land were searched by mechanical diggers.

In the end, however, Mary’s body wasn’t found. She had vanished without a trace.

Today, 42 years after Mary disappeared, the controversial case remains open.

Mamamia’s daily news podcast, The Quicky, investigates why people choose to go missing. Post continues below.

In the decades since, a number of bizarre theories have emerged about what might have happened to the six-year-old girl.

One theory proposed involved Robert Black, a convicted child-killer who often visited Donegal while delivering goods as a cross-border truck driver.

There were also prominent allegations of political involvement after a politician was accused of telling the police not to detain their main suspect.

The case – and its theories – have also created irreparable tension between Mary’s family members.

In fact, Mary’s mother and Mary’s identical twin sister Ann no longer speak to one another.

While Ann believes her mother knows who murdered Mary, the mother-of-three insists she doesn’t know.

Recently, Ann, now 48 years old, has been campaigning for an inquest into her twin sister’s disappearance.

"I do think an inquest is the best thing, as it may lead to Mary being found. There might be something that comes out of it that could help," Ann told the BBC podcast.

"When I asked for the inquest [my mother] wasn't happy about that. And she rang up and she was not happy and she stopped talking, so there's not much you can do about it," she continued.

"It's very tough. I should be able to talk to my mother, but at the minute I can't. A few people have tried to patch us up, but it's not happening at the minute."

But the issues between the mother and daughter didn't just start with the inquest.

"Things totally changed when Mary went missing," Ann explained.

"Life has never been the same since. It made our childhood a lot harder than it should've been. There was an awful lot of tears."

You can find out more about the case of Mary Boyle by listening to BBC's podcast, No Body Recovered, here.

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