Dissenters, reformers, subversives. The nuance in these labels depends, of course, on where you live, and under whom.

How a government behaves towards its political opponents is a window on the principles it holds dear, like no other.

Sometimes there's just no telling how brutal a regime's response to dissent is going to be.

Most of what we heard in the media about the disappearance of Saudi Arabian journalist Jamal Khashoggi, a columnist for The Washington Post, has been known for years now.

He vanished during a visit to the Saudi Arabian embassy in Istanbul, Turkey, in October 2018.

The Dissident presents more by way of detailed explanation to his death than further revelations.

Thanks to the need of Turkish authorities to demonstrate unequivocally that Khashoggi's disappearance had nothing to do with them, we've already heard more than enough about the Saudi journalist's final chapter.

In the narrative of this new film from American documentarian Bryan Fogel, the mystery of Khashoggi's disappearance opens in Montreal, Canada, under a blanket of snow.

It is the city where another, much younger, Saudi dissident, Omar Abdulaziz, hides out.

Abdulaziz, a video blogger critical of the Saudi regime, was a close associate of the late Khashoggi.

Fogel was astute in making his film about Abdulaziz too. It's another story of a political exile that sheds a lot of light on the circumstances around Khashoggi's fate.

The young former associate is currently one of the top influencers in Saudi Arabia. He lives in self-imposed exile, fearing for his life, while family and close friends remain in detention in the kingdom.

It is a wonder that Khashoggi didn't heed his own advice to Abdulaziz, and keep himself beyond the reach of the Saudi regime and its de facto ruler, the crown prince Mohammed bin Salman.

The immense trove of material that Fogel has assembled and expertly woven together demonstrates how Khashoggi was once, unbelievably, a Saudi political insider and supporter of the regime.

With MBS at the helm, some reforms underway, what could possibly be wrong?

Contained in reports from the international news media that Khashoggi was missing was footage of his fiancée, Hatice Cengiz, still waiting for him outside the embassy.

Here there is brief, poignant footage on CCTV of the couple holding hands in the street sometime earlier. Her vigil outside the embassy was still going on 12 hours later.

In a sense, The Dissident takes up where Khashoggi's terrible fate meant he left off, with the story of fellow dissident Abdulaziz and that of academic Hatice Cengiz.

She says her future is now dedicated to Khashoggi.

Each is, in their own way, carrying the narrative forward.

To the extent that documentarians are on a quest for truth, filmmaker Fogel is a brave and committed human rights activist.

His career began in performance as an actor, and, astonishingly, as a stand-up comedian. There's absolutely no trace of any of that here.

At the end of this journey, it seems likely that former insider Khashoggi was killed for what he might eventually say rather than articles he had already contributed to the media.

A high crime indeed.