Earlier this week, Bastian Obermayer, a reporter for the German newspaper Süddeutsche Zeitung, showed me into his “war room,” on the twenty-fourth floor of the paper’s office tower, in Munich. As I entered, he instructed me that I was not allowed to take any photographs. In the center of the room was a cluster of desktop and laptop computers; beyond them, floor-to-ceiling windows looking out onto the dollhouse city. Whiteboards hanging on the room’s walls were covered in complicated-looking diagrams. The computers had never been connected to the Internet, so that they could be used to securely store the 13.4 million files—1.4 terabytes of data—that were leaked last year to Obermayer and his colleague Frederik Obermaier and that have come to be known as the Paradise Papers. In coördination with the International Consortium of Investigative Journalists, three hundred and eighty-one journalists in sixty-seven countries had worked with the leaked information, much of which originated at the Bermuda law firm Appleby, to report stories on how wealthy individuals and companies use offshore accounts to make their fortunes untraceable and unreachable. Those stories began to appear in news outlets around the world this week. At Süddeutsche Zeitung, ten reporters had been dedicated to the project. They had worked in secret since the leaked documents arrived, keeping the topic of their investigation even from other journalists who worked on their floor. “We were always going to get lunch very early,” Mauritius Much, one of the reporters, told me. “We were going at 11:30 A.M., and everyone was thinking, what the hell are these guys doing?” Obermayer added, “This is very German.”

In landing the Paradise Papers, Obermayer and Obermaier (they are not related) were the recipients of one of the largest document dumps in history, second only to Obermayer’s previous career highlight: the Panama Papers, leaked from the Panamanian law firm Mossack Fonseca, which he received in 2015. In the war room, Obermayer showed me the database that the I.C.I.J. had developed to sift through large numbers of files. Its interface looked like Microsoft Outlook, with a search bar at the top. To give me an example of how it worked, Obermayer typed in “Trump”—fourteen hundred and sixty-four hits came up, every document in the cache that mentioned the current U.S. President’s name. On another screen, Obermayer opened iHub, the encrypted Facebook-like forum that the I.C.I.J. created to make collaboration easier across borders and time zones. Journalists working on the Paradise Papers had used iHub, for example, to coördinate research into Nike’s byzantine international registration arrangements. “Everybody went shopping,” Obermayer’s colleague Elisabeth Gamperl told me. Reporters in more than half a dozen European countries went out and bought Nike shoes. Using the tax identification numbers on the different receipts, and the information gleaned from the leaked documents, they were able to determine that sales revenues were not staying in the country where the shoes were purchased but, rather, being funneled to the Netherlands, which has become one of Europe’s tax havens.

I had come to Munich to ask Obermayer how he and his newspaper had found themselves the recipients of these historic leaks, and at the center of this enormous, years-long effort to investigate international financial dealings. Obermayer, who has a long, slender face and wears thick-rimmed black glasses, told me that he was still new to investigative reporting in 2012, when Süddeutsche Zeitung decided to join in the I.C.I.J.’s Offshore Leaks project, the first in a series of reporting projects that paved the way for the Panama Papers and now the Paradise Papers. Obermayer, a former magazine writer, had been moved over to the investigative unit to help improve the team’s writing. While examining the data on that first project, Obermayer came across the name Mossack Fonseca, the Panamanian law firm co-founded by the Bavarian-born lawyer Jürgen Mossack, who moved to Panama in the early nineteen-sixties with his father, who had served in the Waffen S.S.

Obermayer told me that his source for the Panama Papers, whom he refers to as John Doe, had tried to get the attention of several large international outlets, including a U.S. paper, before he got in touch with him. “The leaker didn’t say, ‘Here’s the biggest leak in history, are you interested?’ ” Obermayer said. The first documents that John Doe offered him were not journalistically compelling, at first glance. But Obermayer recognized that they had come from Mossack Fonseca, which he knew operated in extreme secrecy. “I thought, If somebody has obtained data from inside Mossack Fonseca, this could be really interesting,” he said. Knowing the implications of the firm’s name, Obermayer speculated, may have been why he ended up with the Panama Papers.

Süddeutsche Zeitung has, in recent years, pulled even with, or perhaps surpassed, the Frankfurter Allgemeine as the daily newspaper of record in Germany. Its home town, Munich, is a wealthy and politically powerful business hub, with the headquarters of giant corporations such as Siemens, BMW, and Allianz. The paper, a left-of-center institution in conservative Bavaria, traces its origins to the aftermath of the Second World War. Following the war, Allied forces dissolved all existing newspapers in Germany. A group of German journalists, some of whom had worked in opposition to the Nazi Party, received the first printing license issued by the U.S. military’s Munich press office. As the story goes, the same printing press that had been used to print “Mein Kampf,” whose publisher was based in Munich, was melted down and reconfigured, and then used to print the first issue of Süddeutsche Zeitung, on October 6, 1945.

“This is the spirit of this newspaper,” Wolfgang Krach, Süddeutsche Zeitung’s editor-in-chief, told me. “It has to do with the self-consciousness and the attitude of the people here.” Krach, a former investigative reporter with the weekly magazine Der Spiegel, has brought a commitment to investigative work to his current job. After publishing the Panama Papers, in 2016, Krach declared Der Spiegel’s monopoly on investigative journalism in Germany over. Part of this push, he said, arose from the need to secure the future of the paper. “The only strategy to survive in the long run in this very complicated and economically difficult environment is that we have to differentiate ourselves from others, so that people can find in our newspaper something they cannot find anywhere else,” Krach said. After the Panama Papers stories were published, Krach said he received phone calls from editors of major American newspapers, asking not to be left out of the next big leak. “We have been covering globalization and the problems of globalization for twenty years now,” Krach told me. “And we haven’t found an adequate journalistic answer to deal with global issues.” The Panama Papers, he argued, had been the first true global journalism project.

The Panama and Paradise Papers have brought Obermayer renown—and a Pulitzer Prize. The work, he said, was exhilarating. “You get addicted very fast,” he told me. “You can’t let go.” During the two years he’d worked on both projects he tried not to let them interfere with normal life—“I didn’t want to get a divorce,” he said—but late at night, after his wife and children were in bed, he’d often find himself back at his computer, sifting through documents. “Hanging out in the data,” he and Obermaier called it. Obermayer spoke about some of the criticism levelled against the Panama Papers—including the arguments that, because the first leak hadn’t contained revelations about major American figures, the documents must have been fake, or some kind of conspiracy. “This time, with the Paradise Papers, we were so happy when we found many U.S. names,” Obermayer said. “Because we knew, O.K, we won’t be accused of working for the C.I.A. Now they say K.G.B. Which is fine.” U.S. intelligence agencies issued a report stating that Vladimir Putin believed the Panama Papers were an attack against Russia—and suggesting that Russia’s meddling in last year’s U.S. Presidential election may have been a form of retaliation. “When you see the New York Times writing that this thing that started in your living room led to Donald Trump, then you don’t know what to think about it,” Obermayer said, pausing to find the right words. “I mean, I don’t think it’s true. But for a moment, if you read it, it’s just out of control. You know this thing that you started, you cannot take it back.”