By Gordon Corera
Nearly a year-and-a-half after it was completed, the report will be published by Parliament's Intelligence and Security Committee on Tuesday morning.
It is expected to provide an overview of the threat Russia poses to the UK and what has been done to counter it.
It comes after allegations of Russian interference in last year's election, which the Kremlin has said are false.
The report, due to be published at 10:30 BST, is based on secret intelligence material from the UK's spy agencies as well as contributions from independent experts.
It is expected to detail the scale of Russian espionage and subversion against the UK and its allies.
As well as traditional spying and cyber-espionage, it is also expected to explore Russia's willingness to pursue its enemies abroad, including by killing them.
The poisoning with nerve agent of Sergei Skripal in Salisbury in 2018 is one of only a number of recent cases in the UK and across Europe linked to Moscow.
Did Russia meddle in Brexit and Scottish referendums?The report's analysis of Russian interference in the UK political process is likely to be the most closely read aspect.
Operations by Moscow's spy agencies played a significant role in America's 2016 presidential election, and questions have long been raised as to whether there were similar activities in the UK around the 2014 Scottish independence referendum and the 2016 Brexit referendum.
Last week the UK government said they believed Russian actors had tried to meddle in the 2019 general election but this was after the report was finished.
Some media campaigns linked to Russia in previous political events have already been identified and a harder question to answer may be whether there was any significant impact.
Was the UK's response too weak?The report is also expected to raise questions as to whether enough has been done by successive governments to counter Moscow.
The weak response to the murder of Alexander Litvinenko with radioactive polonium in London in 2006, blamed by a judge on the Russian state, is seen as a serious mistake by many observers, including some who gave evidence to the Intelligence and Security Committee.
The response after the Salisbury poisonings is widely seen as having been more effective, especially in the way it brought along allies.
Donations and the influence of Russian moneyBut why has there been a long-term failure to confront Russian activity?
The answer, according to those who gave evidence to the ISC, is the influence of Russia in the UK and especially the power of its money which has seeped deep into public life.
A whole class of people - lawyers, bankers, accountants and public relations professionals - have themselves become wealthy from the Russian money that has flowed into the UK, and particularly into the City of London.
That has created an influential group who have constantly pushed to avoid a hard line on Moscow, including on sanctions.
If the report does pay significant attention to political donations from Russia, this could prove controversial.
One former Russian official, Alexander Temerko, who has donated more than £1m to the Conservatives and whose name has come up in the context of the report, told me last year that he wanted the report published and said that he was a critic of the Kremlin, not its agent.
But it is thought unlikely that the report will name names.
Why was the report delayed?The issue of political donations has been raised by some as a reason for Downing Street not allowing the report to be published before last December's election.
But one insider suggested, instead, it was what they described as "the tale of two Dominics".
And that Dominic Cummings, Boris Johnson's chief No 10 adviser, did not want to give a platform to Dominic Grieve - the former chairman of the ISC who had the Conservative whip withdrawn over Brexit and who stood unsuccessfully as an independent at the election.
After many rumours, the public is now finally getting a chance to see the report. But it will not see everything.
Some parts are expected to be redacted or censored. And there is also a classified version which will be for official eyes only.