Early this morning, Nicola Sturgeon announced she would be giving an "important speech" today in the grand surroundings of Bute House, her official residence.
Among SNP sources, the chatter was that she would give an ultimatum to Theresa May that if she could not negotiate a differentiated Brexit deal for Scotland she would push for a second independence referendum.
Forget that. Scotland's first minister has gone the whole hog, saying she will next week push the button on a second independence referendum by putting legislation to the Scottish Parliament.
Sturgeon can probably win that in Holyrood, but can she win the referendum?
Her announcement will delight her many many supporters.
She is undoubtedly a hugely effective and talented politician. During the last referendum, the SNP's support grew very significantly and they managed to enthuse many thousands of new members to their cause.
But does the SNP have an updated economic argument? Is she willing to risk rancour from many Scottish voters who want another referendum like a hole in the head?
As I've written before, the UK and Holyrood governments are set for a battle royal over timing of a potential vote.
But the question first is whether or not the prime minister is willing to grant a vote. Under the law, Westminster has to grant the referendum; it's not just down to the Scottish government.
I'm told Number 10 had carefully worked out "countermoves" depending on what the first minister's message was this week.
Now Sturgeon has made the first big move, it's down to the other side to respond.
But arguably we have just entered into the most complicated, most fraught, most fundamental period of political uncertainty for our country in a very long time.
Sturgeon's announcement confirms that it is not just our place in the EU that is changing, but the relationships between our own nations that are at question too.

The 53-year-old German was last seen on Saturday afternoon, when he went to cycle part of the South West coastal path between Newquay and Sennen.
The search involved the coastguard helicopter, cliff teams, lifeboat crews and police.
Devon and Cornwall Police said a body was recovered by the Sennen lifeboat near Land's End.
A police spokesman said he was unable to confirm the identity of the dead man.

The runaway critter was spotted on top of the house in Cambridgeshire.
Fenland Animal Rescue was called in, but it was "a bit of a wrestle as he was not the friendliest of raccoons", said the charity's Josh Flanagan.
"That said, I've never met one before, and we don't train in raccoon rescue techniques," he added. They are hoping to locate the animal's owner.
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"Raccoons aren't native to this country, so he must have escaped from somewhere," Mr Flanagan said.
"You can imagine their surprise when the householders saw one on their roof.
"The woman thought her husband had lost the plot, but when she looked out, there it was, staring back at her through the window."
With the animal jumping from the house to a garden shed roof, it was a short game of "cat and mouse" as Mr Flanagan tried to catch him.
"At one point I was sat on the rooftop with him, and we were both eating bananas. I don't think I'll ever experience anything like that again, but it's why I do this job," he said.
Eventually the animal was brought down safely, using a control pole.
A few days after its ordeal, the racoon is settling in - but "causing havoc" - at the rescue centre's Whittlesey base.
"He's a devilish boy, a bit vicious," Mr Flanagan said. "They look all cute and adorable, but they're not."
If no one comes forward to claim him, he will be moved to a specialist rescue centre "where he can live his life in a safe and secure environment with other raccoons to call friends".
Before the Parliamentary drama over the first part of Brexit is even done, another dramatic twist in this most tangled of plots.
[NEXT_CONCEPT]
A search team looking for a missing tourist have found a man's body at the foot of cliffs in Cornwall.
[NEXT_CONCEPT]
A woman thought her husband had "lost the plot" when he woke her up to tell her there was a raccoon on their roof.