With the help of the CIA, German investigators foiled what would likely have been the most devastating terror attack of its kind in the country’s history. The plans of a fanatical group of Islamists trained in Pakistan reveal just how great a risk Europe faces. It was early June at the G-8 summit in the German seaside resort of Heiligendamm, and climate protection and hedge funds were the key issues on the agenda. But then there came the moment when the news of a potential terrorist plot reached Chancellor Angela Merkel. Not a word of it was mentioned in the summit’s official communiqu_s. Merkel and US President George W. Bush met alone to discuss what he called “the Pakistan matter.” America felt threatened, and the threat, US intelligence agents told their president, was coming from Germany — once again, just as it had on Sept. 11, 2001. Bush, who was well briefed about the plot, even knew the names of the suspects. He made it clear to Merkel that he was taking the matter very seriously. Her officials at the Chancellery were all too familiar with what the US president was talking about. “Operation Alberich,” as the intelligence agencies called the case, had top priority.