When Theresa May dreamt of becoming PM as a little girl, she could scarcely have imagined this: negotiating the biggest deal Britain has ever had to strike since the end of World War Two.
It's the political test of her life.
And of all the challenges which lie ahead - the 'divorce' bill, Scotland, Northern Ireland and the rest - there are few which match the scale and complexities of the Brexit trade deal.
Get it right and it could herald a new age of prosperity for the UK. Get it wrong and we could all end up the poorer.
So we decided to take the Tonight programme on the road to see where we all might be headed; from a hillside farm in Wales to hi-tech engineers in Exeter; from Northern Ireland's border to the private office of the Scottish first minister; and from Yorkshire all the way down to Dover, where businesses across the UK are watching and waiting.
We don't even know when the trade deal talks will start yet.
But what we do know is this: we are out of the single market and out of the customs union.
If Britain does want a unique and comprehensive deal - no 'half-in, half out' - what on earth will it look like?
Our Welsh lamb farmer is afraid of a big new deal with a country like New Zealand, which could flood our market with cheaper meat.
Our high-tech engineer worries that, out of the single market, he won't be able to move his products from England across France at speed.
But Yorkshire businessmen David Smith and son Luke are thrilled with the prospect of trying out new markets.
They make huge bendy plastic safety barriers for big industry and are looking forward to bending and breaking through the borders of Europe's customs union, where Britain will be able to make global trade deals on its own, rather than the EU operating on its behalf.
When you hear all these different voices you get a glimpse of how big and how crucial the trade deal is.
Then throw in factors like the 27 EU members who've got to agree to it, and toss in 'The Trump Factor' for good measure.
Whether you're in business or not this is going to affect your life.
If you want to navigate what it's going to mean for the pound in your pocket, our economy and our standing in the world, we'll help you do it.
- Watch Deal or No Deal? Brexit Britain – Tonight on ITV and the ITV Hub at 7.30pm