Already it is becoming the biggest U.S. political scandal since Watergate, and threatens to destroy Donald Trump's presidency.
The FBI this week revealed explosive new allegations of Russian collusion in last year's American election as a special prosecutor charged three former aides to the President.
If true, the claims are the clearest suggestion yet that Trump knew the Kremlin was trying to help his campaign by providing "dirt" on Hillary Clinton, according to Daily Mail.
During the election, the Russian government hacked Democratic computer accounts and released a trove of embarrassing emails related to the political machinations of his Democrat rival which helped put him in the White House.
The characters embroiled in the scandal include Trump's former presidential campaign chief, who is accused of siphoning off US$75 million ($108m) through an offshore account, a Maltese professor living in London said to be a link man with the Kremlin, a woman posing as a niece of Vladimir Putin and Trump's own son.
As Trump scrambles to distance himself from those under suspicion, we describe the dramatis personae at the heart of the political scandal convulsing America.
The London go-between
Hailed as an 'excellent guy' by Donald Trump after he hired him as a foreign policy adviser, the fresh-faced, London-based American lawyer is now co-operating with the FBI and may be the man who ultimately forces Trump out of the White House.
During the election campaign, Papadopoulos repeatedly tried to arrange a meeting between Trump and the Russian government, which he was told had damaging information about Mrs Clinton, according to FBI files.
The 30-year-old, a graduate of University College London and the London School of Economics, was initially mocked for his youth and inexperience when he was named as foreign policy adviser to the Trump campaign in March 2016.
After meeting a London-based academic named Professor Joseph Mifsud - who allegedly has close ties with the Kremlin - while travelling in Italy in mid-March 2016, Papadopoulos was introduced to a woman he wrongly believed was a niece of Russian leader Vladimir Putin.
She later wrote to him: "We are all very excited by the possibility of a good relationship with Mr Trump."
Papadopoulos used his new contacts repeatedly to try to arrange a meeting between the Trump campaign and Russian government officials, according to court documents.
He passed back his conversations to the Trump inner circle, outlining offers for Trump to visit Moscow. One of his bosses in the Trump campaign praised his efforts as "great work".
After allegations of Russian meddling in the U.S. election emerged, Papadopoulos was first interviewed by the FBI in January this year.
He initially claimed that the contacts he'd had with the Russians happened before he joined the Trump campaign.
But he was arrested at Washington Dulles Airport on July 27, where he admitted the charge of lying to FBI agents about the timings, and has since been cooperating with the special prosecutor Robert Mueller.
He faces five years in jail for perjury, which could be reduced as part of a plea deal.
The White House has played down Papadopoulos as a low-level adviser on the campaign.
But Mueller told the court at Papadopoulos's indictment hearing last month that he did not want the arrest made public because it would "significantly undermine Papadopoulos's ability to serve as a proactive co-operator", indicating that he may have agreed to wear a wire to record conversations with some of his former colleagues.
It means he may have spent the past few months secretly gathering incriminating evidence from the inner circle of Trump's campaign staff on behalf of the FBI, which could potentially bring down the administration.
The Maltese Prof
The British-based professor with close ties to Russia allegedly acted as the link between Trump's campaign and Putin's regime. Professor Mifsud told George Papadopoulos that Moscow had "dirt" on Hillary Clinton in the form of "thousands of emails", the FBI documents claim.
It is alleged that after the former Maltese government official (who works at the London Academy of Diplomacy - which is affiliated to the University of Stirling in Scotland) met Papadopoulos in March 2016 while travelling in Italy, the following month - just days after Trump named Papadopoulos as one of his advisers - they met again in London.
This time, it is claimed, the professor brought a Russian woman who posed as Putin's niece, and said she had connections to senior Russian government officials.
Mifsud allegedly later told Papadopoulos that he had just returned from Moscow, where he had learned from high-level Russian government officials that Russia had damaging information on Mrs Clinton.
The academic has confirmed he was the London professor described in the document drawn up by special counsel Mueller, but vehemently denied any wrongdoing. He said his links with Russia were purely academic and nothing to do with the government, adding: "I have a clear conscience."
The campaign boss
President Trump's former campaign chief was the most high profile of the trio charged by the U.S. prosecutors this week.
The veteran Republican strategist is accused of a money-laundering conspiracy that syphoned off US$75m ($108m) from pro-Kremlin political groups.
The cash is said to have helped fund a lavish lifestyle, with Manafort splashing out millions on property, antiques and designer clothes.
After hiding the cash in a labyrinth of offshore accounts, it's alleged he spent US$5 million ($7.2m) to refurbish a home in the exclusive Hamptons area of New York state, and moved more than US$3 million ($4.3m) to his own accounts to pay for his children's school fees and decorate his mansion in Virginia.'
The FBI accuse him of working for the Russia-backed Ukraine government - which was toppled in 2014 - and its pro-Kremlin Party of Regions political organisation between 2006 and 2015.
He denies a string of charges of dodging taxes, illegally working as an unregistered agent of a foreign government and making false statements to federal investigators, which carry a maximum sentence of 20 years.
But U.S. legal commentators believe the threat of a long spell in jail could prompt him to cooperate with the investigation.
Manafort previously advised the presidential campaigns of Gerald Ford, Ronald Reagan and George Bush Snr., while his Washington lobbying firm has represented corrupt dictators Ferdinand Marcos of the Philippines, and Mobutu Sese Seko of the Congo.
He agreed to work without payment for Trump in March 2016 and was quickly made campaign chairman. But he was sacked three months later after the discovery of a ledger indicating he had received millions of dollars in secret payments from the Russian-backed Ukrainian Party of Regions.
Separately, Manafort was also allegedly involved in discussions with campaign aide George Papadopoulos about setting up meetings with the Russian government during the election. Papadopoulos emailed a high-ranking Trump campaign official on May 21, 2016, with the subject line "Request from Russia to meet Mr Trump".
Manafort forwarded the email to another campaign official, stating: "We need someone to communicate that DT is not doing these trips," referring to a trip to Russia. "It should be someone low level in the campaign so as not to send any signal."
Manafort also attended a meeting with Donald Trump's son, Donald Jnr, and a Russian lawyer where Russian "dirt" on Mrs Clinton was allegedly discussed.
The FBI first swooped on Mr Manafort's home in Virginia in the summer, picking the lock in a pre-dawn raid amid fears he might destroy evidence if they banged on his door.
Mr Manafort this week was allowed to turn himself in and denied the charges at a Washington court, where bail was set at US$10m ($14.5m). He was ordered to live under house arrest.
The Washington lobbyist
A long-term business partner of Paul Manafort, having met him as an intern at his Washington consultancy 25 years ago, Gates was this week arrested in the U.S capital. Mr Gates, 45, faces similar allegations of working for the Russia-backed Ukraine government.
In his consultancy work he has sealed private equity deals in Russia and Eastern Europe with pro-Kremlin oligarch Oleg Deripaska, who was barred from entering the United States over allegations relating to links to organised crime. Deripaska denied the allegations.
Gates joined Trump's campaign as a lobbyist at the same time as Manafort last year and, even after Manafort was forced out, he remained in the inner circle and later played a key role in the President-elect's Inauguration committee.
He denies the allegations and was bailed on a US$5m ($7.2m) surety.
The President's son
Donald Trump Junior
The hapless oldest son of the U.S. President has also been dragged into the growing scandal over the Trump campaign's links to Russia.
Trump Jnr joined the Republican campaign manager Paul Manafort in a meeting with a female Russian lawyer in 2016 to discuss "dirt" they had on Hillary Clinton.
Donald Trump Jnr asked his brother-in-law Jared Kushner - who is married to Ivanka Trump - and Manafort to attend a sit-down meeting with Natalia Veselnitskaya.
Trump Jnr tried for months to deny the existence of last summer's 30-minute meeting on the 25th floor of the Trump Tower in New York.
But after a newspaper investigation, he was forced to reveal an email chain setting up the meeting, in which he declared, "I love it" after being told that Russians had documents that would "incriminate Hillary and her dealings with Russia, and would be very useful to your father".
The power behind the throne
The multi-millionaire husband of Donald Trump's daughter Ivanka has quickly risen to be the President's most trusted aide, despite complaints of nepotism.
Kushner, 36, admits attending the meeting last year with Donald Trump Jnr and the Kremlin-linked lawyer, but said he had no idea it had been arranged in the hope of gaining political leverage over Mrs Clinton.
He also insisted he had been too busy during the election campaign to read an email exchange Donald Trump Jr had sent him that made clear the Russian government wanted to pass on incriminating evidence against Mrs Clinton to help secure a Trump victory.
Realising the meeting was a "waste of time", he claimed, he emailed his assistant to ring him to give him an excuse to leave.
But, disturbingly, he also admitted he had contact with the Russians four times during the election campaign and the transition period before Mr Trump took office, including meetings with Russia's U.S. ambassador Sergey Kislyak and Russian banker Sergey Gorkov - a close friend of Putin.
This includes a December 2016 meeting, where it's claimed he discussed setting up a secret back channel with Moscow.
He strenuously denies discussing anything improper with Russian officials, and insisted he wasn't guilty of any collusion. But investigators want to know exactly why he failed to disclose these meetings initially.
The long arm of the law
Former Marine Robert Mueller was appointed special counsel for the Russia investigation in May.
The no-nonsense operator has previously prosecuted crime bosses, foiled terror attacks and faced down earlier Presidents.
The Vietnam veteran took over as FBI director the week before the September 11 attacks and spent the next 12 years transforming the agency into a battle-hardened, terrorism-fighting force.
He served mainly under George W. Bush, but was so well respected on all sides of the political divide that he was asked to stay on by Barack Obama when he took office.
As a federal prosecutor and later head of the Justice Department's criminal division, he oversaw high-profile prosecutions against such targets as Panamanian dictator Manuel Noriega and New York crime boss John Gotti.
Now, he's pursuing a case that is already proving to be the biggest of his career.