The world was able to witness, understand, and respond to the horrors of September 11 largely through the medium of photography. The 9/11 attacks, in fact, were the most widely observed breaking-news event in human history, seen that day in still photos, on the Internet, or on television by an estimated two billion people, nearly a third of the human race. The following is the tale of one man, Mike Rambousek, who lost his son Luke that morning, five years ago this month. Rambousek, oddly enough, was able to channel Luke’s memory through the power of a single, horrific picture.

Mike Rambousek sits in front of his Hewlett-Packard computer, pulling up a chair for a visitor. He fiddles with a file on the desktop and clicks on a photo, the one that he says is “not a bit pleasant.” It shows people standing in the windows of the north tower of the World Trade Center a few minutes prior to the building’s collapse.

Before discussing the picture, though, he stops to talk about waking up on September 12, after the longest day of his life.

That Wednesday, Mike Rambousek arose, alone, in his cramped Brooklyn apartment. His wife, Jindra, was at their summer mobile home, in Damascus, Pennsylvania, unable to return to the city because of security roadblocks. Lining the apartment’s walls were his and Jindra’s collections from their native Czechoslovakia: delicate marionettes, antique clocks, and coffee cups, some dating back 150 years. And there, near the far window, were row after row of vinyl records that their son Luke would spin as a D.J. at a Brooklyn dance club during his off-hours. For a day job, Luke, 27, was a computer-maintenance temp at eSpeed, a Cantor Fitzgerald subsidiary, working on the 103rd floor of 1 World Trade Center. The Rambouseks’ apartment was quiet that morning, and Luke’s bed was empty.

The day before, says Rambousek, “I saw the picture [on TV] at nine o’clock. People thought, Cessna. I called Luke’s office and the phones were ringing. And I thought, He’s O.K. I’ll go pick him up and bring him lunch.” Mike assumed that the office would dismiss Luke after a plane accident, so he packed the usual—pepper steak and diced watermelon—and planned on sharing a meal near the towers, to be followed by a “walkabout,” as Mike called it, a ritual stroll around the nearby streets that father and son had enjoyed for years.

Mike and Luke were especially close. Both were enamored of electronics; Mike, now 59 and retired, had been a computer-systems engineer. Both worked in the World Trade Center—Mike during the 1990s, Luke starting in early 2001. Both revered Mike’s father, Ota, a virulent anti-Communist, now in his 80s and living in Prague. Ota, who had taken part in the Prague uprising against the Nazis, in 1945, had been jailed after the war on charges of spying for the U.S. He would later take part in the reform movement during the Prague Spring, of 1968. Following the Soviet crackdown that year, he escaped to Italy, then to the States. (Ota would later be decorated by President Ronald Reagan “for his outstanding patriotism.”) Having faced down both the Nazis and the Communists, Ota encouraged his son and grandsons, Luke and his older brother, Martin, to take challenges head-on, and to stand up for their principles.

“I suddenly got a feeling that Luke’s gone . . . I suddenly knew.”

Only one other period in Mike’s and Jindra’s lives had been as long and as anguished as September 2001 would prove to be: a stretch in the late 1970s when they were stripped of their Czech citizenship, forced onto a plane, and eventually allowed to immigrate to America. “I had a quite decent job as a chemist, but they tried to put me into the slammer,” Mike recalls. Neighbors and strangers turned out to be informants, he says; potential promotions were quashed. “Because we were relatives of American spy,” he says, “we were on the top of party shitlist.” His existence in those days had seemed like a passage torn from Kafka or Solzhenitsyn.