Christopher Steele, former British intelligence officer. Steele worked for MI6 in London, Moscow, and Paris before leaving the service and founding his own corporate intelligence firm, Orbis, in 2009. This photo was taken as he returned to work in March 2017 after a period of lying low. Courtesy of AP Images

The young spy. Steele spent three years in Moscow between April 1990 and April 1993. He had a front-row seat to history. Steele was on duty during the KGB-led coup of August 1991. He walked into town and watched from fifty yards away as Boris Yeltsin climbed onto a tank and denounced the plotters. Courtesy of Anatoly Andronov

Steele was based at the British embassy in Moscow. He traveled across newly accessible parts of the Soviet Union and became the first foreigner to visit Stalin’s secret bunker away from the front. This photo, taken in early 1991, shows him with newspaper editors in the Tatar city of Kazan. Courtesy of Anatoly Andronov

Steele’s famous dossier, written in MI6 house style. The dossier runs to thirty-five pages. Steele wrote it between June and December 2016. It was based on information from secret sources and alleges that Trump received intelligence from the Kremlin on rival Hillary Clinton. Moscow had been “cultivating, supporting and assisting TRUMP for at least 5 years.” Courtesy of BuzzFeed via DocumentCloud

In the summer of 1987, Trump traveled to Moscow for the first time with his wife, Ivana. The photo shows them in Leningrad. Trump was a guest of the Soviet government and the state travel agency Intourist—a branch of the KGB. His hotel room next to Red Square would have been bugged. Courtesy of Maxim Blokhin/TASS

General Vladimir Kryuchkov, KGB foreign intelligence chief. In 1984 he circulated a secret note to KGB station chiefs abroad, urging them to do more to recruit Americans. They should exploit personal weakness and use “creative” methods, ­including ­“material incentives.” Courtesy of TASS/TASS/Getty Images

Trump in Moscow again for the 2013 Miss Universe beauty contest. His host was Aras Agalarov (middle, next to his son, Emin), an Azeri-born property tycoon. The pair discussed building a Trump Tower Moscow. The project never happened but was still being secretly discussed in 2015–16 as Trump campaigned for president. Courtesy of Victor Boyko/Getty Images Entertainment/Getty Images

Moscow’s glitzy Ritz-Carlton, at the bottom of Tverskaya Street. According to the Steele dossier, Trump watched two prostitutes perform a show in his presidential suite. The FSB spy agency recorded everything, it says. Trump denies this. Courtesy of Alex Shprintsen

Agalarov’s pop-star son, Emin, sang at Miss Universe and became friendly with Trump. Emin is pictured with his British publicist, Rob Goldstone. In June 2016 Goldstone sent an email to Donald Trump, Jr., offering “incriminating” Russian government material on Hillary. Courtesy of Aaron Davidson/Getty Images Entertainment/Getty Images

For months, Donald Trump, Jr., denied meeting Russians. Actually, he accepted Goldstone’s email offer, replying with the words: “I love it.” A secret meeting took place in June 2016 at Trump Tower. Details leaked a year later. Courtesy of John Moore/Getty Images News/Getty Images

A midlevel Russian lawyer, Natalia Veselnitskaya, flew in from Moscow to meet with Donald Jr. in Trump Tower. Also present were Paul Manafort, Jared Kushner, and Rinat Akhmetshin, a lobbyist who worked in Soviet counterintelligence. Courtesy of Yury Martyanov/AFP/Getty Images

Mafia boss and racketeer, Vyacheslav Ivankov was a legendary figure in the Soviet and Russian underworld. In 1992 he moved to a new theater of operations: America. The FBI spent three years looking for him. The agency eventually tracked down his hiding place—Trump Tower.

Moscow’s ambassador to the United States, Sergey Kislyak, meeting Trump in the Oval Office, in a photo taken by the Russian foreign ministry. Kislyak’s father, Ivan, was a top KGB spy who served in European capitals, including Athens and Paris, where he was a ­rezident in the 1970s. Courtesy of Alexander Shcherbak/TASS/Getty Images

During the campaign, Trump repeatedly praised Russia’s president, Vladimir Putin. The two finally met at the G20 summit in Hamburg. Later that evening, Trump talked to Putin over dinner without his U.S. interpreter. What they discussed is unknown. Courtesy of REUTERS/Carlos Barria

Trump’s future national security adviser, Michael Flynn, sitting next to Putin. The 2015 event was a dinner to celebrate the tenth anniversary of RT, the Kremlin’s propaganda channel. On a previous Moscow visit, Flynn toured the HQ of the GRU, Russia’s military spy agency. Courtesy of AP Images

Lawyer, lobbyist, and adviser to dictators. Paul Manafort joined Trump’s campaign in the spring of 2016. He was on intimate terms with ex-Soviet oligarchs, including Putin’s ally Oleg Deripaska. In July 2017 the FBI raided Manafort’s apartment as part of its collusion probe. Courtesy of AP Images

Carter Page, Trump’s foreign affairs adviser. Page worked in Moscow, where—in the words of one Russian spy—he “got hooked on Gazprom.” The dossier alleges that he held secret meetings with Igor Sechin, Putin’s de facto deputy, and a Kremlin aide. Page denies this. Courtesy of REUTERS/Sergei Karpukhin

Trump was increasingly vexed by what he called the “Russian thing.” In May 2017 he fired the man who had failed to make it go away—FBI chief James Comey. Comey’s Senate testimony was a riveting piece of political history. His firing came about after Trump asked for “loyalty,” and Comey refused. Courtesy of Chip Somode­villa/Getty Images News/Getty Images

Enter the prosecutor. In the wake of Comey’s firing, former FBI chief Robert Mueller was appointed special counsel. His remit: to investigate allegations of “coordination” between the Trump campaign and Russia. Mueller’s heavyweight team didn’t leak. It appeared to be following the money. Courtesy of AP Images

The president’s unfireable son-in-law. In December 2016 Jared Kushner met with Kislyak and asked if it would be possible to set up a secret back channel to Moscow. Kushner held another meeting with Sergei Gorkov, a banker-spy, in Trump Tower. Courtesy of AP Images

In 2008 oligarch Dmitry Rybolovlev purchased Trump’s seaside Florida mansion for $95 million, $50 million more than Trump paid for it in 2004. The Russian never lived there and eventually demolished it. During the ­campaign, his plane was spotted on the tarmac next to Trump’s—a coincidence, Rybolovlev said. Courtesy of REUTERS/Eric Gaillard

Putin’s scowling gatekeeper and the head of Russia’s biggest oil producer, Rosneft. The dossier claims that Sechin offered Page the “brokerage fee” on a privatization deal worth billions, with U.S. sanctions on Moscow dropped in return. Page denies this. Courtesy of Sasha Mordovets/Getty Images News/Getty Images

Russian foreign intelligence ran an undercover spy ring in Manhattan. The FBI busted it. Two Moscow spies had diplomatic immunity, but the third, Evgeny Buryakov, didn’t. In 2015 Buryakov pleaded guilty to espionage and got thirty months in jail. Courtesy of AP Images