Explainer: Why Boris Johnson can't legally force a no-deal, but can't call an election either
All you need to know
What have the Brits done now?
MPs have approved a piece of legislation that seeks to block a crash-out Brexit by 327 votes to 299 - a majority of 28.
If brought fully into the law, the bill requires the UK government to ask for a Brexit extension beyond October 31 unless a deal is approved by Parliament or Parliament agrees to a no-deal exit by October 19.
In bizarre scenes in the Commons, an amendment from backbench Labour MPs seeking to bring back former prime minister Theresa May's final Brexit deal that offered concessions following cross-party talks, the Withdrawal Agreement Bill, was approved without a vote.
Didn't Boris Johnson say the UK was leaving the EU at Halloween 'do or die'?
Yes, the prime minister said he was taking the UK out "come what may". He has reacted angrily to the move by MPs, expelling a number of high-profile Conservative MPs who voted against him.
So what's the prime minister's game plan?
He has warned there will be "consequences" for the vote.
Mr Johnson says he will not go to Brussels seeking another delay because it would "hand control of the negotiations to the EU".
He wants to have a general election on October 15.
Does that mean another snap election in mid-October?
Not necessarily. The UK now operates 'fixed-term parliaments' of five years.
In order to collapse the House of Commons, a prime minister needs a two-thirds majority. Labour leader Jeremy Corbyn has said his party will not vote for an election unless and until the anti no-deal bill has passed.
Is the main opposition party trying to stop an election?
These truly are extraordinary times. Mr Johnson finds himself boxed in.
He legally won't be able to crash-out of the EU on October 31 and he won't be able to call an election. The shift in power is as unprecedented as it is dramatic.
What does it mean for Ireland?
There is renewed hope that a no-deal scenario can now be avoided, although it's still not clear how.
Irish Government sources note the House of Commons has repeatedly rejected the idea of a crash-out - even if they can't agree on an actual way forward.
Even if fresh negotiations do start, the backstop will still be a problem for the UK, so it's not over yet. Preparations for a no-deal Brexit will have to continue unabated.
What does the EU make of it?
Events in Westminster are being closely monitored in capitals across Europe.
There is likely to be a major debate between member states about whether to allow the UK to delay Brexit again.
Some key figures, including French President Emmanuel Macron, were hesitant about granting the last extension.
What has Charles Stewart Parnell got to do with it all?
In one of the more surreal moments on Tuesday night, the ghost of the Irish Home Rule leader appeared to enter the House of Commons.
As the debate got heated, leader of the house Jacob Rees Mogg said: "The approach taken today is the most unconstitutional use of this house since the days of Charles Stewart Parnell when he tried to bung up parliament."
And Winston Churchill?
The wartime leader is a hero of Mr Johnson, but that hasn't stopped him from removing the party whip from his grandson.
Nicholas Soames voted to block no deal, and will now be dropped from any Conservative election ticket.
He described being deselected as the "fortunes of war".