Rebel MPs seized control of the Commons from ministers tonight adding a new element of chaos to the Brexit endgame.
A cross party group coordinated by Tory Oliver Letwin and Labour's Yvette Cooper won a vote tonight that will mean MPs dictate what the Commons debates and votes on on Wednesday.
The move is constitutionally unprecedented and sets the stage for 'indicative votes' on the options for Brexit if MPs will not support the divorce deal negotiated by Theresa May.
MPs has resisted rumours the Government would set up its votes on seven options - the existing deal, cancelling Brexit altogether, a new referendum, a Norway-style soft Brexit, a Canada-style hard Brexit, a UK-EU customs union or No Deal.
Instead they want MPs themselves to come up with options - with a view to putting those with the broadest basis of support to the whole House.
The moves leave wide open the kind of Brexit Britain might try to navigate to if MPs reject the deal a third time this week, or Mrs May abandons the vote in anticipation of defeat.
It all comes against a backdrop of furious rumours Mrs May is on the brink of being ousted by her Cabinet. The risks appear to have receded this morning after weekend claims ministers were poised - but despite there being no procedural way to remove her a public withdrawal of political support would finish her.
This is your guide to what happens next:
What happened tonight?
MPs have finally done what they have threatened to do for months: Seized control of the Commons agenda so they can stage their own debates and votes on Brexit. It is constitutionally unprecedented.
What does it mean?
This will only become clear in the coming days but in the first instance it means rebel-controlled debates on Wednesday about indicative votes on a possible Brexit solution.
It will mean the Commons directly voting on a range of options more expansive than Mrs May's deal or No Deal for the first time. The conclusions will not be legally binding but be politically significant.
What kind of Brexit will MPs vote for?
Nobody knows for sure. The assumption of most people in Westminster is Parliament would vote for a much softer Brexit than that on offer by Mrs May. This would likely mean staying in the EU Customs Union and Single Market.
Brussels has said it would accept this in the right circumstances but it would break most of Mrs May's red lines - the ability to strike trade deals, to escape the European Court and almost certainly free movement of people.
Will May be forced out by her Cabinet?
The immediate risk appears to have receded since rumours of a Cabinet coup spread like wildfire over the weekend. There is no procedural way to remove her - but a public withdrawal of political support would finish the PM.
What was agreed at the EU summit last week?
EU leaders have approved a two-part delay to Brexit following late night talks.
Brexit is set to be delayed until April 12 whatever happens next week, giving the UK an extra two weeks.
If MPs pass the Brexit deal before then, the extension will run until May 22.
What does it mean?
The immediate risk of the UK leaving without a deal on Friday, March 29, is effectively over - subject to a change in UK law but this should be a formality.
Brexiteers will still believe they can secure a No Deal exit on April 12 while Remainers will see it as an opportunity to lock in a much longer delay.
Will there be a third vote on the deal and when will it be?
Mrs May says she will only have one if she can win this time - but is still working on it. Most currently expect it to be held tomorrow night but this is not fixed. Thursday is also under consideration.
Can she win?
It looks unlikely. The prospect of No Deal on April 12 will encourage Brexiteers they should vote down the deal a third time.
There is currently little sign the DUP are being won over by a political offensive behind the scenes.
Mrs May also alienated Labour MPs with her angry speech on Wednesday night.
It seems possible she could end up losing the third vote by a bigger margin than the 149 votes she lost the second one.
What if she does win?
If the PM manages a great escape, then Britain will be on track to leave on May 22. The Government will move quickly to get the necessary laws in place.
What if she loses?
The EU has made clear that if the deal goes down a third time, Britain must come back with a plan in time for the new deadline of April 12.
Most urgently, a decision will have to be made on whether the UK takes part in European Parliament elections on May 23. If it does not, there will be No Deal - and Mrs May says electing MEPs would be the wrong thing to do.
However, there is still a majority of MPs in Parliament against No Deal so the choice could be taken away from the PM.
If elections are agreed in the UK there will probably be a new EU summit around April 10 to approve a much longer extension - perhaps to the end of 2019 or even longer.
The UK will have to have a new plan for what to do with the time as Brussels has made clear it cannot keep going over the same deal.
Will MPs vote on other options?
Probably. Tonight's vote could setup a full-blown 'indicative vote' that would set all the options against each other. A defeated Government could stage the same procedure.
There are claims the Government would put up seven options: Mrs May's Deal, No Deal, Revoking Article 50, a Second Referendum, a Customs Union soft Brexit deal, an even softer Customs Union and Single Market deal, and a Canada-style Free Trade Agreement deal.
The idea would be to find what kind of Brexit might be supported by Parliament or if there is none, see if there is support for a new public vote.
Will May resign?
Nobody knows. No Prime Minister has ever soaked up so much humiliation and carried on and yet Mrs May is still in Downing Street.
She suggested last week she would not accept a long delay beyond June 30, seen by many as a hint she would resign if it had to happen.
A third defeat for the deal this week would also provoke huge calls for her to resign.
A move to No Deal could also see some Tory MPs join with Labour to force the Government out with a vote of no confidence.
What happens to Brexit if May goes or the Government collapses?
It is hard to know. Even with a tweak to the law to change the date, Brexit will still happen with No Deal on April 12 if other choices keep being rejected.
But we also know there is a majority of MPs against a No Deal Brexit. It is possible there are enough Tory MPs prepared to remove the Government to stop No Deal by installing a Corbyn government ahead of a snap election.
Only the Government can bring forward the necessary change in the law to change the Brexit date.
What is Labour's position?
Labour says no deal must be stopped - but also says it will not vote for Mrs May's deal.
It wanted a three month delay to renegotiate the political declaration on the final UK-EU relationship but this would require it form a Government more or less immediately.
Were it to do so, it would try pass the divorce deal attached to a new political declaration that said the final relationship would be based on a permanent customs union.
It has passed no comment on the actual proposed delay.
Will there have to be a new election or a referendum?
This falls into the anything is possible category. Parliament is deadlocked and has been for months - which suggests an election is necessary.
And yet the governing Tory party clearly has little idea what it would put to the country or who would lead it into an election. An election can be forced without the consent of the Tories but it is very difficult.
Similarly, it is far from clear there are the votes for a referendum in the Commons. The idea was crushed last week because Labour did not vote for it.
Will Brexit ever happen?
Almost three years after the referendum, this depends entirely on your view of events. The law says it will but there are enough MPs to at least change the date if given the chance to do so.
It could now happen on April 12 or May 22. Or it could be delayed much further.