Without fanfare, Chernobyl has become unmissable TV.
The Sky Atlantic show, which concludes on Tuesday, is harrowing and unrelentingly bleak, with some complicated science to get to grips with.
It is also a western-made drama about a disaster that occurred in the Soviet Union more than 30 years ago, of which details such as the number of deaths are still debated. There was much that could go wrong.
And ultimately, we know how the story pans out.
But seemingly from nowhere, this five-part mini-series is now the show that everyone is talking about. (Sorry, Game Of Thrones).
After just three episodes, Chernobyl topped film and TV database IMDB's list of the greatest 250 TV shows of all time. It currently has a score of 9.7, based on more than 96,000 votes. Fan-voted charts obviously have their problems and are by no means definitive, but it is still quite an accolade for a drama series just four weeks and four episodes old.
To put it into context, Game Of Thrones (73 episodes and eight years old), scores 9.4, with more than 1.5 million reviews.
It is a gripping show. But what is it that has made the series so popular? We spoke to a nuclear scientist, a TV writer and a journalist who was born and raised in the Soviet Union to get their views.
Claire Corkhill, assistant professor in nuclear waste disposal at the University Of Sheffield
"I didn't know much about the show beforehand. I think quite often with dramas based around scientific events you tend to roll your eyes because there's a tendency to overdramatise, to elaborate, to put things in that aren't true just to make the story more interesting. But I was completely blown away by how accurate this is; there must have been so much research that has gone into it.
"There are tiny scientific details that are really accurate. There was a scene with the roof showing all the debris, the graphite, the twisted metal. They've done their research. And when it showed the firefighter exposed to the radiation and very sick early on, this is 100% true. People didn't die immediately, they were very sick and death came later.
"The story does tell itself. The historical event was extremely dramatic so you've got the basis for a good story, but there was so much that could have been done badly that wasn't. It's very clever.
"I think the reason it is doing well is first of all because it's a true story. Also, the writing itself is seamless.
"Watching the show I wanted to help the ordinary person understand some of the science behind it. I find when I talk to the public about nuclear waste people are always very interested. These are materials that are going to be radioactive for hundreds of thousands of years. The question is, 'what do we do with them?' I think the industry has an element of being shrouded in secrecy and it is the role of scientists to explain.
"I am surprised [it has been so popular] and really pleased by the interest. We generate 11% of the world's electricity from nuclear power and in the UK alone we have enough nuclear waste to fill Wembley Stadium. It's an issue that not many people think about."
:: Dr Corkhill has been tweeting throughout each episode, helping to explain some of the science discussed on screen. Follow her tweets @clairecorkhill
Chris Bennion, TV writer for The Times
"The very obvious and fundamental thing to say about Chernobyl is that it's very, very good. It's a really high quality, really classy drama from the top to the bottom; it's brilliantly written – which almost comes as a bit of a surprise as Craig Mazin was previously known for the Hangover 2 and 3, and now he comes through and writes this really powerful drama
"The casting is superb and the detail is really, really spot on, from the costumes to the setting to the tiniest little things. It was clearly important for him to get it absolutely right.
"Another thing about its appeal, for us here in Britain and I'm sure lots of other places in the world, Chernobyl has always had this powerful effect on the imagination, something of the unknown and terrifying about it. It's almost amazing that it's taken so long for someone to do a proper serious drama about it because it is a source of endless fascination.
"They have also tapped into the idea of how Chernobyl almost signalled the death of the Soviet Union; it exposed some ugly truths to the world about what they'd been covering up. I think that's really interesting.
"I was looking forward to it [before it aired] but primarily because the cast was so good. The central three – Jared Harris, Stellan Skarsgard, Emily Watson – I'd like to watch those three in anything. So I was looking forward to it but I didn't imagine it would be so serious. I thought it might be a bit more of a thriller, given a lighter treatment. Maybe glossier, slicker. Craig Mazin – and Johan Renck, who directed it, he's known for pop videos – have proved me wrong. It's remarkable and they have made some really bold choices. It's bold and brave and really mature, that's what's really impressed me.
"I don't think [the IMDB rating] is a massive thing but it does tell you something, doesn't it? I'm always a bit wary about setting too much store in things like Rotten Tomatoes and IMDB because you can get some odd things happening, but it does tell you that it's hitting people.
"For me as a critic, you watch this and think this is brilliant, this is the stuff that people really should be watching, so to know that they are is heartening. It's obviously not a big show like Game Of Thrones but it's almost rolled along on word of mouth. It's a big budget show but not a mega series that no one can escape from, so I absolutely wouldn't have guessed it would do this well. It's great to see a work of this quality getting recognised."