Prime Minister Boris Johnson has said the UK will leave the EU on 31 October "do or die" - even if it means walking away without a deal.
Many people oppose a no-deal Brexit, with MPs planning to take action in Parliament and others taking action in the courts. But can no deal be stopped now that the government has decided to suspend Parliament?
A no-deal Brexit means the UK would immediately leave the EU with no agreement in place about the "divorce" process - or how they separate.
Overnight, the UK would leave the single market and customs union - arrangements designed to help trade between EU members.
Many politicians and businesses say this would damage the economy.
Others say the risks are exaggerated.
Former prime minister Theresa May couldn't persuade her own MPs to support her agreement with the EU, which would have avoided no deal.hat's why she resigned.
Unless Mr Johnson can get his own - as yet non-existent - Brexit deal passed, the UK will face the prospect of leaving without an agreement at the end of October.
The alternative would be to extend the deadline again - or cancel Brexit altogether.
In theory, unless a new plan is agreed, Mr Johnson does not need to do anything for a no-deal Brexit to happen.
This is because the UK's departure on 31 October is already written into law. He could just run the clock down.
But it's not as simple as that.
Most MPs in the UK Parliament are against leaving without a deal. And they could try to stop it from happening.
Despite having little time, MPs still have options for trying to block a no-deal Brexit.
Legislation emerged as the preferred course of action, following aross-party meeting of MPs opposed to a no-deal Brexit.
What happens in Parliament is usually up to the government of the day, so MPs would have to find a way to wrest control of the timetable.
You might hear the phrase "SO24" over the next few weeks. This refers to Standing Order 24, the rule that allows MPs to ask for a debate on a "specific and important matter that should have urgent consideration".
These debates usually have no power to force action. But it would be possible to give them more teeth if House of Commons Speaker John Bercow allows amendments.
For example, MPs could try to take control of the timetable for a day, to try and force through a whole piece of legislation.
The new law could simply force the PM to request an extension to the Brexit deadline.
Theoretically, there is enough time for this.
Any new law has to pass through all stages of both Houses of Parliament. This would usually take weeks, but it could be done in as little as three days. This happened in April when Yvette Cooper managed to rush through a piece of legislation to force an extension.
But even if MPs managed to force it through in three days, they would probably have to allow for a day to secure and another day to hold the emergency debate. With as few as four sitting days before parliament is prorogued, this could be tight.
One hurdle could come in the House of Lords. Although opponents to no deal have a large majority, peers wanting to block a piece of legislation could talk and talk until there is no time left.
Seen by some as the "nuclear option", MPs have the option to vote out the government.
This could happen as early as 4 September, the day after Westminster returns from its summer break.
If a majority of MPs vote against the government, a formal process kicks off under the Fixed-Term Parliaments Act:
A period of 14 calendar days allows the prime minister to prove he holds the confidence of Parliament
During this time, if another MP can prove they hold the support of a majority of MPs the current prime minister is expected to give way
If no government has been formed after 14 days, a general election will be triggered. This would take at least five weeks
After holding a vote of no confidence, MPs would only have a few sitting days to form an alternative government and prove it has majority support in the House of Commons, rather than the full 14 days.
It is unclear what would happen if the PM lost a no confidence vote and Parliament was suspended before the 14-day period was up.
But technically it would leave no more time to form an alternative government and we would slide towards an automatic election.
There are only two options that will rule out no deal altogether, rather than postpone the deadline: pass a deal, or cancel Brexit altogether.
It is still possible for MPs to approve a new deal before exit day. This is the course of action ministers say they prefer.
The PM could return from the EU summit in mid-October with a brand new deal, propose it to MPs and get it passed in time for the 31 October deadline.
But the main hurdle here would be whether he has enough time to pass the legislation that is needed to implement the deal - a much more complicated process than the stop-no-deal law.
It isn't just Parliament which could get in the way of the PM's prorogation plans - a number of legal challenges are making their way through the courts.
In Scotland, a judge has refused to order a temporary halt to plans to shut the UK Parliament. But full hearing of the caseill be heard on Tuesday 3 September.
The action is being taken by a cross-party group of 75 politicians, who want the court to rule that prorogation would be illegal and unconstitutional.
Cases are also being started in Belfast and London, both seeking injunctions to block the closure of Parliament.
Northern Irish campaigner Raymond McCord is waiting to hear the result of his challenge.
And Sir John Major is joining forces with campaigner Gina Miller. The former Conservative prime minister believes Parliament is being closed to prevent MPs from opposing a no-deal Brexit.
If any injunction to block prorogation is granted, the government would immediately appeal and all three cases could end up in the Supreme Court.