Presented by Kirsty Wark
In an election which has been completely transformed by the television debates - tonight might be the night that crystallises enough votes to make a big difference come next Thursday's polling day.
The debate finishes at 10 o'clock and Newsnight will be on air just half an hour later with a specially extended edition.
We'll bring you the edited highlights and our political and economics editors will analyse the key moments.
We'll also have the first snap polls and reaction from senior politicians.
Will Gordon Brown refer to his behaviour yesterday when his public actions seemed to contrast with private vitriol? Having been caught calling a long time Labour voter "bigoted", Mr Brown said he was "mortified", but will he repeat his apology to the Rochdale grandmother on air tonight?
And how will David Cameron and Nick Clegg deal with the matter? Politicians are not held in high regard as a species after the expenses scandal, so will the two men concentrate on policy not pot-shots?
The first half of the debate tonight will deal with the economy - and today The Economist came out for the Conservatives - a blow for Gordon Brown, but will each of the men respond with more detail to possible questions on the deficit?
We'll be drilling down into their answers with our Political Panel Danny Finkelstein, Peter Hyman and Olly Grender, who'll also be giving their sharp observations of how the three performed...
We'll get the atmosphere from Emily who will be in the chaos of the spin room getting reaction from the three parties.
Justin Rowlatt will be looking at the reaction from viewers - from the acid comments on twitter, to the ups and downs of "the worm".
And at the low tech end, Stephen Smith is in his usual spot at the motorway services at Donington on the M1 where he'll be finding out what the Motorway Men and Women thought of the debate.
And how will the newspapers report it tomorrow? We'll have the latest editions.
Join us at 10.30pm.
Kirsty