MPs will hold a string of votes tonight that could lurch the UK into a soft Brexit - and rip the Tory party in two.
The 'indicative votes' will allow MPs to choose between a string of options for Britain's future outside the EU, just 11 days before we're meant to leave.
Theresa May must decide whether to accept the result or keep pushing her own thrice-defeated Brexit deal before an emergency summit on April 10.
So what are tonight's indicative votes and why are they so important?
Here's a full explanation of the options before MPs.
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What are Brexit indicative votes?
Indicative votes are where MPs indicate what they might vote for on Brexit , not just what they vote against.
Theresa May's Brexit deal has already been voted down three times, by 230, 149 and 58, in three separate votes in the Commons.
So MPs took control of the Commons agenda in a historic move to stage the votes and find a way forward - against the government's will.
This is the second time MPs have staged indicative votes on Brexit. The first time, on March 27, eight options were voted on.
The most popular were a customs union and a second EU referendum, but none won a majority. Now MPs are trying to whittle them down.
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What time are the indicative votes tonight?
MPs will vote from 8pm on up to nine prospects for Britain's future (see below).
Speaker John Bercow only selects the final list to put to a vote at around 6pm.
Voting takes half an hour, with the results then counted by Commons authorities and announced probably at around 10pm.
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How does indicative voting work?
MPs troop into the wood-panelled No and Aye Division Lobbies next to the Commons chamber - and are handed a single green ballot paper.
Each ballot paper contained a list of the options and two boxes next to each one - yes and no. MPs can tick either box for each option, or no box at all.
Once again, MPs can choose as many 'yes' and 'no' options as they like.
The number of votes for and against each option will be announced, and a full breakdown of MPs voting for each will be available on the Commons website.
Brexit indicative vote results in FULL: How MPs voted on options for UK's future
What are the indicative vote options?
There are expected to be 9 options which will then be whittled down to perhaps four by Commons Speaker John Bercow.
1. 'Amend' the deal and leave on May 22
A gang of Tory Brexiteers want to "amend" the 585-page Withdrawal Agreement with the EU - so the UK can exit the Irish backstop unilaterally.
That is despite Theresa May's two months of talks, which aimed at amending the Withdrawal Agreement, ending in failure.
Instead, the PM was forced to bring home a new document "bolted on" to her plan which said the backstop - a clause which could extend EU customs rules over the UK from 2021 - will not be permanent.
Despite this, the Brexiteers - including John Redwood and Andrew Bridgen - believe this can still be achieved and the UK will leave the EU on May 22.
HOW MPs VOTED LAST WEEK - N/A, NEW PROPOSAL
2. No Deal Brexit on April 12
A motion backed by hardline Brexiteers and led by the Tory MP John Baron says the UK should leave the EU without a deal on April 12.
This is pure Brexit, favoured by hardliners - and the legal default if no deal is agreed. No trade terms and no transition. Chaos widely predicted.
HOW MPs VOTED LAST WEEK - FOR: 160, AGAINST: 400
157 Tory MPs voted to back No Deal in a display of the level of hostility May's deal still faces on her back benches. Three Labour MPs - Dennis Skinner, Kate Hoey and Ronnie Campbell - also voted to crash out without a deal.
3. Customs union
The leading 'soft Brexit' motion, this would force the government to negotiate a "permanent and comprehensive UK-wide customs union with the EU".
It would mean bolting that customs union onto Theresa May's deal - changing it dramatically and softening our relationship with the EU.
A customs union means we follow EU customs rules - without a say on them.
It would solve the problem of whether to hike tariffs and checks on goods crossing the borders - thus solving some of the Irish border issue too.
But while this would cut out a lot of paperwork, Theresa May says it would block us from signing trade deals with other countries around the world - and breach the Tories' 2017 manifesto.
The motion is tabled by Tory veteran Ken Clarke and backers include Labour's Yvette Cooper, chair of the Commons Brexit Committee Hilary Benn and Tory former minister Sarah Newton.
HOW MPs VOTED LAST WEEK - FOR: 264, AGAINST: 272
MPs voted to defeat Ken Clarke's call for a customs union by just 8 votes. There were 12 Labour rebels and 13 independents who voted against - including ten of the newly formed Independent Group.
4. Common market 2.0
This is another 'soft Brexit' plan - proposing UK membership of the European Free Trade Association and European Economic Area.
This would commit us to free movement of people through continued participation in the single market, and a "comprehensive customs arrangement".
It is tabled by Conservatives Nick Boles and Andrew Percy and Labour's Stephen Kinnock, Lucy Powell and Diana Johnson.
The scheme would remain in place until a wider trade deal which guarantees frictionless movement of goods and an open border in Ireland.
HOW MPs VOTED LAST WEEK - FOR: 188, AGAINST: 283
Most of The Independent Group did not back the motion. They were joined by Lib Dem Wera Hobhouse - she was the only member of her party to oppose it.
5. A second EU referendum to 'confirm' any deal
This motion would trigger a second EU referendum - specifically to let the public either confirm the deal struck by MPs, or remain in the EU.
Organisers claimed a million marched in London in favour of a second referendum but others are bitterly opposed.
The motion was drawn up by Labour MPs Peter Kyle and Phil Wilson and after much horse-trading, won the support of the Labour Party.
HOW MPs VOTED LAST WEEK - FOR: 268 , AGAINST: 295
Labour told MPs to back the motion but 27 voted against including Melanie Onn - who resigned to break the whip. If half of the Labour MPs who opposed the motion had voted the other way it would have passed.
6. A second EU referendum to prevent No Deal
Tory Remainer Dominic Grieve has tabled plans to hold a second EU referendum - specifically to prevent a No Deal Brexit .
It stops short of forcing the government to hold a public vote.
But it says it would be "appropriate to commit" to one "if it were necessary" to prevent a No Deal Brexit.
HOW MPs VOTED LAST WEEK - N/A, NEW PROPOSAL
7. Revoke Article 50 and hold a public inquiry
SNP MP Joanna Cherry says if there is still no deal the day two days before Brexit day, the Commons should vote on whether to crash out with no deal.
If MPs reject No Deal (which they're expected to), the UK would immediately revoke Article 50 - cancelling Brexit. This is a proposition backed by more than 6million people in a petition.
The UK would then hold a full public inquiry on whether the UK will be able to accept any model of Brexit that is acceptable to the EU.
If there is a second referendum, it would then be held on whether to approve the model proposed by the public inquiry.
This is an expanded, more detailed version of a proposal put forward by Joanna Cherry last week.
HOW MPs VOTED LAST WEEK - FOR: 184, AGAINST: 293
Ten Tories backed calls to revoke article 50 - including Ken Clarke and two Foreign Office ministers Alan Duncan and Mark Field. But a whopping 111 Labour MPs backed the motion - despite it not being party policy.
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8. Soft Brexit through EFTA and the EEA
A motion tabled by Conservative MP George Eustice - who quit as agriculture minister to fight for Brexit - proposes remaining within the EEA and rejoining EFTA, but remaining outside a customs union with the EU.
This would mean keeping free movement with the EU. It's similar to the much-feted 'Norway option' for soft Brexit but not the same.
The motion was also signed by Conservative MPs including former minister Nicky Morgan and head of the Brexit Delivery Group Simon Hart.
HOW MPs VOTED LAST WEEK: FOR: 65, AGAINST: 377
9. Labour's plan for a softer Brexit
Labour is expected to re-table a motion proposing its plan for a close economic relationship with the EU.
The plan includes a comprehensive customs union, with a UK say on future trade deals.
There's also close alignment with the single market; matching new EU rights and protections; participation in EU agencies and funding programmes; and agreement on future security arrangements, including access to the European Arrest Warrant.
We've seen this plan before and it's been voted down before.
HOW MPs VOTED LAST WEEK - FOR: 237, AGAINST: 307
Unsurprisingly they voted on party lines - but astoundingly four Labour MPs didn't back it. Including Jarrow MP Stephen Hepburn.
How will it tear the Tories apart?
Tory MPs are warning of the worst party split since the Corn Laws 173 years ago if MPs force a softer Brexit in the 'indicative votes'.
170 Tories have written to Theresa May warning her not to accept a customs union - the most likely option to pass.
Yesterday Justice Secretary David Gauke said if MPs choose a customs union, the Prime Minister must listen.
And in a rare interview, Chief Whip Julian Smith said a soft Brexit was "inevitable" after Theresa May lost her majority in the snap election of 2017.
But Cabinet minister Chris Grayling today warned a customs union would essentially keep the UK in the EU.
And Tory Brexiteer Jacob Rees-Mogg warned he could not support the idea.
It's thought Theresa May could put her Brexit deal to a FOURTH round of voting this week - possibly in a run-off between MPs' indicative choice.
But that risks more deadlock after her DUP allies warned they won't back her deal... even if she puts it to a vote 1,000 times.
