In the spring of 2010, Christopher Steele, a former British spy with a shock of graying hair and a quiet, understated manner, received some alarming news: Vladimir Putin, a lifelong ice hockey fan, had taken a sudden interest in soccer.

This was years before Mr. Steele compiled his now famous dossier on Donald Trump, with its references to clandestine meetings in Prague and, of course, “the pee tape.” In 2010, Mr. Steele, regarded among those who knew him as a serious and levelheaded MI6 officer, had only recently retired and opened his private intelligence firm in London. He might have reasonably expected to be embarking on an uneventful, if lucrative, second career. But the story of what happened next would profoundly affect his and countless others’ lives, foreshadowing the Trump investigation and the shadowy role Russia plays in the modern world.

Among Mr. Steele’s first clients was a group of wealthy individuals and corporations supporting England’s bid to host the 2018 World Cup. The tournament hadn’t been held in England since 1966, and the country’s soccer-mad populace was desperate to do so again. England invented the modern-day game in the 19th century and, at the outset of the 21st, believed it was uniquely poised to host, with dozens of world-class stadiums, hotels, highways and airports ready. The British government chipped in £2.1 million of the bid’s more than £17 million total cost, and international celebrities including Prince William, David Beckham and David Cameron, then the prime minister, promoted the effort.

Mr. Steele had been hired, in large part, because of his expertise in Russia, one of six countries vying for the right to host the tournament. In the early 1990s, he had worked undercover in Moscow, and he maintained extensive contacts in Russian government and business circles. His mandate in the spring of 2010 was to find out anything he could about the competing bid. He was no stranger to Russia’s playbook. When it came to pursuing national objectives, the country had few if any compunctions about employing whatever means — collusive, corrupting, scandalous — might be necessary. And on its face, it was clear the Russian bid was going to need a lot of help.