Miguel Ángel Gil is at 4,000 feet in a business-class seat at the front of an Airbus A340 flying over Provence in the south of France. He is wearing a dark suit, tie askew as usual, and is carrying just an overnight case with him in the overhead locker. It's 8.40 p.m., on the last weekend in May, and it's his 53rd birthday.

In Milan, at that very moment, Atlético Madrid is about to start the Champions League final against Real Madrid – the second meeting of the teams in three years at the climax of the competition. Inside the stadium, 20,000 Atléti fans fill one end of the Giuseppe Meazza stadium, better known as the San Siro, which has played host to some of football's greatest teams. Stretched from one side to the other, they hold up a huge banner reading “Your values make us believe”. Even though they are outnumbered by Real Madrid supporters, it is the Atlético fans that make most of the noise. They scream “Atléti, Atléti…”. UEFA's idea of hiring pop star Alicia Keys to play a short set just nine minutes before the match was perhaps ill-advised.

The previous night Gil had listened to the Milan Philharmonic Orchestra perform Strauss at the city's other famous arena, the La Scala opera house. He had also dined at the theatre, which is decorated in gold brocade and red velvet, with Real Madrid president Florentino Pérez and other officials.

After the meal, Gil had slept at the smart Meliá Milano hotel, a 10-minute drive from the stadium. After a low-key lunch with fellow shareholder Enrique Cerezo to celebrate his birthday – they closed the curtains of the hotel's function room – Gil went to his room to pack his suitcase.

At 6.40 p.m., just as the players were leaving for the stadium, Cerezo and other Atlético directors posed for a group photograph on the marble staircase to mark the occasion. Gil had already gone. He had ordered one of UEFA's fleet of hired black limousines, on call for the weekend, to take him to Milan's Malpensa airport to catch Iberia flight IB3255 home to Madrid. As usual, he was too anxious to watch the game. If he felt too tense to watch Atlético play even Spanish league games, there was no way he was going to sit through the Champions League final.

At the stadium, Cerezo sat alongside Spain's King Felipe VI, one of the few Atlético fans in the Spanish establishment. Alongside them was Gianni Infantino, Michel Platini's UEFA lieutenant between 2009 and 2015, who had told his boss about transfer market investors working with Champions League clubs in the midst of the financial crisis.

Unusually, there was no sign of Platini at the San Siro. For years, as UEFA president, he had been the man who had handed over the silver Champions League trophy known as “orejones” (“big ears” in Spanish, because of its looping handles that resemble two ears). Platini would hug the players of the winning team and try to console the losers. As a former player, he could empathize with them. But now he was banned from the stadium. He had been kicked out of the sport he had been in love with since the age of seven when he played table football at the Café des Sportifs his grandfather owned in the French town of Joeuf. Two weeks earlier, the UEFA president of eight years stepped down from his post after being banned from all football activities for four years.

Platini's downfall was the latest fallout from the American investigation into FIFA. That inquiry had prompted the Swiss to launch their own probe into the not-for-profit organization that had been based in their country since the 1930s, when it moved into a 30 m² office in Zurich's ritzy Banhofstrasse. In May 2015, a couple of hours after FIFA executives were arrested at the Baur au Lac hotel in a dawn raid, Swiss police slipped into the organization's headquarters and seized hard drives and other documents. They had already quietly ordered Swiss banks to hand over details of FIFA financial transactions dating back years.

After poring through the data over several weeks, the investigators came across one unusual exchange involving the two most powerful men in world football. In February 2011, a few months before Platini announced he would not stand against Blatter in FIFA presidential elections, the ruling body had wired 2 million Swiss francs to a private bank account of the Frenchman. Armed with this information, the police and prosecutors returned to FIFA headquarters. With Blatter and other FIFA executives meeting underground in their usual spot, seated around the blue “lapis lazuli” floor, the Swiss state officials walked into the building to search the president's office before summoning him for questioning.

Blatter protested his innocence, saying that the single payment to Platini was made on a verbal agreement more than a decade earlier in 1999, when the former player began a three-year stint working as his advisor. At the time, Blatter said, FIFA was having financial difficulties. It was only in 2011, by which time FIFA had more than $1 billion in cash reserves, that Platini had asked to be paid.

Under Swiss law, there was nothing illegal about the arrangement. Yet, for FIFA's head of compliance, Domenico Scala, both men had breached their fiduciary duties by not recording the sum in FIFA accounts when the agreement was made. The ruling body's ethics committee banned both men from football for eight years and, although the sentences were subsequently reduced following appeals to four years for Platini and six years for Blatter, both men were now nursing their wounds.

Platini's stand against commercialism in football was also undermined soon after when, as part of a leak of documents from the Panamanian law firm Mossack Fonseca, it emerged that he had opened an offshore company in the tax haven called Balney Enterprises Corporation in 2007, less than a year after becoming UEFA president. Platini, whose main residence was in the Swiss village of Genolier in the foothills of the Jura mountains, said he had done nothing wrong: authorities in the country knew about the company and all his tax affairs were in order.

After losing his job, Platini kicked his heels, spending time playing golf with old friends on courses outside Paris and on the French Riviera. He was trying to “disconnect” from football, but he could not stop talking about it. He kept up a jovial front – “Am I allowed to play football in my garden?” he joked – but it was difficult for him to take, and he was already plotting a way back. At the age of 80, Blatter had no such aspirations. He had returned to the Swiss village of Visp where he was brought up.

With Platini now unable to carry through with plans to stand as FIFA president, Infantino stepped in as a candidate and, after using his political experience, fluency in five languages, some generous promises (and with the help of €500,000 from UEFA to cover his travel and campaign costs), he was elected. It was a sudden and unexpected turn of events, even for the polyglot. He now sat alongside King Felipe VI as the most powerful man in football: FIFA president.

Infantino said he was saddened by Platini's ban but would cherish “the great things” they had achieved over the previous nine years, presumably including in his mental summary the “financial fair play” rules and ban on investors from the transfer market. He now planned to continue their work as the most senior official in football. His FIFA election manifesto pledged to create “fair and transparent” player trading, FIFA, he wrote, needed to take a more hands-on approach to the transfer of footballers, to “limit abuse and tackle the exploitation of the system by external parties”.

Even as he sat alongside the Spanish King, lawsuits swirled around the FIFA ban of investors from the transfer market and Neymar's move to Barcelona. In the latest development a few weeks earlier, a judge at Spain's National Court had dropped charges against the former Barcelona president Sandro Rosell. A separate case brought by Brazilian investor Delcir Sonda against Rosell, Neymar and his father was still moving slowly through the Spanish courts.

Sitting back in his business-class seat, Gil could finally try to relax a little. For the next hour or so, he had no obligations to perform as Atlético chief executive, and no way of knowing what the score was in the Champions League final. There were a thousand thoughts going through his head, all the same. Could the team, his family's heirloom, finally win its first elite European title? All the stress over the debts his father had left would be forgotten with the silver trophy. Only 22 clubs had won the European Cup since 1955 and as money played a bigger role in football, it was becoming more difficult for all but the biggest teams to win.

Winning the league two years earlier had been very special, but the Champions League would top that achievement. Atlético had earned €94 million in UEFA prize money for reaching the final and quarter final the last two years, and could look forward to another handsome payday. The club had reduced its mountainous tax debt from €120 million to about €40 million – still more than enough to be shut down in another league, but a marked improvement on three years earlier – and was pushing ahead with drawn-out plans to build a new stadium. However, triggering happiness among Atlético's legion of loyal fans – including his family and friends – would be more rewarding than the financial spinoffs of becoming European champion.

Gil and thousands of supporters had suffered enough by losing in extra time two years ago. Another loss against Atlético's arch rival would be difficult to take. Just as he was deep in thought, as the Airbus A340 passed over the seaside resort of Cannes, a teenage Atlético fan with her hair in braids in the Milan stadium burst into tears. Sergio Ramos had put Real Madrid in the lead. It was Ramos who had punctured Atlético's dream two years ago in Lisbon, with a last-gasp 93rd-minute goal.

Gil was oblivious to the torment Atlético fans in the stadium were suffering when the Iberia plane touched down in darkness at Adolfo Suárez airport in Madrid at 10:22 p.m. The match was deep into the second half and Real Madrid was still leading 1-0. As the pilot taxied to the terminal, Atlético's Belgian substitute Yannick Carrasco smashed the ball into the roof of the net to level the score.

As Gil emerges into Madrid's airport and comes out into the arrivals hall, a man recognizes him and tells him the game is now in extra time. A television reporter follows him up the escalator to the car park, jabbing questions at him. “Wouldn't it be great to win the Champions League on your birthday?” asks the reporter, grinning. “Of course, it's something we have been trying to do for 113 years” Gil says, with a tight smile. “Now please leave me in peace.”

He wants to be alone at the wheel of his new Range Rover, driving in the night and listening to music until the match is over. The pace of the match slows, because both teams are tired and cautious not to make a mistake. The final will be decided by penalty kicks.

Gil is already safely behind the wheel of his new car and driving along the empty highway. At homes and bars in Spain, 13 million people – more than one quarter of the country's population – are watching the penalty shootout get underway. Real Madrid scores its first three penalties and so does Atlético. It's a tie, and the final could now be decided by a single mistake.

To the horror of Atlético fans, Juan Francisco “Juanfran” Torres steps up and smashes his kick against the post. Cristiano Ronaldo needs only to convert his for Real Madrid to win the final. He plants the ball firmly into the net, rips off his shirt and races to the side of the field to celebrate with his teammates. Juanfran breaks down in tears as he holds his bony hand to his heart and mouths “I'm sorry” to thousands of Atlético supporters.

The Atlético players are stony faced and wave away acting UEFA president Ángel María Villar as he tries to put the runner-up medals around their necks. Instead, they snatch the silver discs in their hands without looking at them, as if collecting a leaflet from a street hawker. At about the same time, while still at the wheel on a ring road on the outskirts of Madrid, Gil finds out the bad news.