For 17 days this month, Dutch columnist Ebru Umar was held against her will in Turkey, legally barred from leaving the country. Her alleged crime: insulting President Recep Tayyip Erdogan. But after extended negotiations between the two governments, the controversial, outspoken Umar finally returned home to Amsterdam on May 11.

But she is hardly free, and certainly not home safe: threats against her life mean she cannot return to her apartment. She stays in safe-houses in "undisclosed" locations. She must notify police of her whereabouts at all times. Officials have offered bodyguards, though she refuses.

Yet while she still faces prosecution – and a potential four-year jail sentence – in Turkey, it is neither Erdogan nor his government that poses the real danger. It's the Dutch.

Or rather, it is Dutch-born men and women of Turkish ancestry, who continue to issue threats against her life.

In fact, it was Dutch Twitter users who reported Umar, herself of Turkish heritage, to the Turkish police for her obscenity-laced, anti-Erdogan postings on her Twitter feed, sent out from her vacation home in Kusadasi. And it is Dutch youth, mostly appearing to be in their 20s, who have since posted things like, "The Mosque has collected funding to rent a crane to hang you when you arrive at Schiphol." Another stopped her in the street in Turkey and snarled, "I know where to find you in Holland. You know what happens after death?"

Consequently, while there is much to be said about Ebru Umar's plight and about what Dutch officials call "the long arm of Erdogan," the real story isn't actually Ebru Umar. The real story is the Netherlands, or really, all of Europe, where Muslim immigrants have largely failed to integrate, where much of the current generation is notably more religious and conservative than their parents, identifying more with their lands of ancestry and values than with their own.

Now, as Europe faces a massive new influx of Muslim immigrants and refugees, that story, as Umar herself insists, demands attention, because the threats to Umar these past weeks have not been made by indigenous Dutch. Rather, those who have threatened Umar in recent weeks are, like Umar, the children or grandchildren of Turkish immigrants. But unlike Umar, none of them has assimilated into Dutch culture. Though born and raised in the Netherlands, they view Turkish law as their law, Turkey's leader as their leader. And so, also unlike the secular Umar, they support limits on free speech that would criminalize blasphemy (such as cartoons of the Prophet Mohammed), and apparently in some cases, view even insulting the president as a capital crime.

Translated, the tweet reads, " In the depths of my heart I hope she will be executed as a warning to the rest of the idiots."

In this, their call for violence reveals a full-color illustration of the violent extremist undercurrent roiling beneath Europe's 4 million-strong Turkish immigrant population.

Umar is elegantly coiffed, wearing a white scarf draped around her neck and sparkling, dark-blue earrings at an Amsterdam restaurant some days after her return. Her phone, which has been scanned for spyware since her return, has just been handed back to her, as have her car and house keys. Though she remains in danger, she is gradually re-entering her world.

As we talk, I am surprised to find that the woman of such strong words, known for her frequent use of expletives on social media and in her newspaper columns, is in fact quite soft-spoken, with a melodic voice that belies the fury of her writing.

And nowhere is that fury unleashed more than in her attacks against what she calls "Nederturks" – Turkish-Dutch who are starting to turn their fury back at her. But it is clear that, even after her ordeal in Turkey, she has no plans to limit her criticisms to her writing. To the contrary: she has plenty to say out loud – not just about the Turkish-Dutch – but increasingly about the Dutch themselves.

In many ways, it is the Dutch Umar largely blames for her situation. The Netherlands, she says, is on a "sliding slope," in which the country's legendary freedom is becoming increasingly limited, largely because of the pressure, sometimes violent, from "Nederturks" and other Muslim immigrants. "We are totally not interested in foreigners," she says, speaking of the Dutch. "We are so focused on 'don't touch me, I won't touch you' – but meantime we close our eyes. Deliberately close our eyes."

And by now, it may be already too late to change the situation. "It's like you have a garden," she says, "and your garden isn't fenced. And someone takes a step into your garden, and you tolerate that; so the person takes another step. And even another step. And you go, 'my garden is big enough.' 'My garden is still big enough.' 'Oh, I don't need a garden anyway.'"

Her words prove prescient – not just about the Netherlands, but Europe at large. Only three days after we met, German courts banned a satirical poem by comedian Jan Boehmermann that mocks Erdogan, calling him a "goatf*cker" and alleging that he enjoys child porn. It is just the latest in a long list of songs, poems, plays, cartoons, art works, and other forms of expression that have been censored as a result of pressure by either Muslim immigrants or protests in the Muslim world.

In Umar's case, such protests have a terrifying precedent. In 2004, Dutch filmmaker and columnist Theo van Gogh was shot and stabbed to death by a Muslim extremist who took exception to his film "Submission," which exposed the oppression of Muslim women. Umar and van Gogh were friends. In fact, he gave her her first break as a columnist. And like Umar, van Gogh was frequently the target of threats. Like Umar, he refused a security detail. It is not surprising that his parents and friends now caution her that her situation is a bit too much like his.

That opponents of van Gogh and Umar turn to violence is also, she feels, the fault of Dutch tolerance and willful blindness. But there is in fact more to it than this, particularly in the case of "Nederturks." Erdogan has frequently urged European Turks to resist assimilation, which he calls "a crime against humanity." (Other "crimes against humanity" to Erdogan: Zionism, "Islamophobia," and the European response to the refugee crisis.)

Instead, Erdogan believes Europeans of Turkish heritage should keep their Turkish values, which are founded on the concept of "namus," or honor. Namus, for instance, is why Muslim girls whose parents find them "too Westernized" face honor violence (and in the Netherlands, most honor killings are perpetrated in the Dutch-Turkish community). It is why insulting the prophet, or "dishonoring" his name, is punishable in most Muslim countries by death. And it is why insulting the president of Turkey is punishable by prison, or, for the most extreme of Umar's detractors, execution.

But Umar believes there are additional factors involved. Whatever his oppressive politics, in his previous role as prime minister, Erdogan oversaw a massive economic boom and grand expansion projects that profoundly modernized Turkey. Roads improved. Health care improved. "I don't like Islamists, I don't like Erdogan," she says. "But how come all of a sudden developments in infrastructure are available to bigger parts of the population than prior to Erdogan?"

This was very much a tactical move on Erdogan's part, she says. "He did it very cleverly. He made it available to the poor areas. And that is always the majority of the country. You get into their brains from a child on. You get them educated at Islamic schools, and so on." As a result, Islamism is also growing among his fans, including in Europe, "because they're mad [enthusiastic] about everything Erdogan did – and so they are mad about everything he does, including fanatic Islamism."

And with fanatic Islamism comes the violence, not just prison, for blasphemy or insulting the nation, but hanging, flogging, execution. This likely will not happen in the Netherlands, but such things set a tone. They open the door to brutality.

Yet in some ways, Umar almost seems as blind to that brutality as the politicians she criticizes. In the weeks before his murder, Theo van Gogh often insisted that nobody would really kill him. "I'm the village idiot," he would say.

Umar is similarly cavalier. The mindset of those who threaten violence in response to things she's said or written is one of "plain stupidity, blind hatred," she says. "They have no idea what they're doing."

Yet history shows they know exactly what they're doing, as Mohammed cartoonist Kurt Westergaard, who was attacked in his own home by a Somali intruder brandishing an axe, can attest. So can van Gogh's family and friends, along with the families of Charlie Hebdo's slain editors. Is Umar too afraid to recognize this about her own life? Is Europe, about the future of its culture?

Last Wednesday, the Dutch Parliament held a formal debate on the Ebru Umar issue. A day prior, Umar penned a column for Metro describing what she was bringing to the discussion: clear demands that the parliament recognize the total failure of multiculturalism; that form be given to plans to integrate asylum-seekers, refugees, and others before handing them a Dutch passport; and "respect for our Dutch freedom."

They are demands the rest of the Western world would do well to consider, too. Fail to meet them, and we may all soon find that we no longer have a garden anymore.

Abigail R. Esman, the author, most recently, of Radical State: How Jihad Is Winning Over Democracy in the West (Praeger, 2010), is a freelance writer based in New York and the Netherlands.