Daniel Pearl aspired to be a “universal person,” says his widow, Mariane Pearl, in “The Journalist and the Jihadi: The Murder of Daniel Pearl,”a new documentary airing tonight on HBO. Tragically for Pearl, a reporter for the Wall Street Journal fascinated by the Muslim world, it was his fate to cross paths with Ahmed Omar Saeed Sheikh, an Englishman of Pakistani descent who had already achieved a cosmopolitanism beyond Pearl’s capabilities — and then brutally renounced it.

The relationship between these two men — their backgrounds, how they came to meet in Pakistan in early 2002, Sheikh’s subsequent abduction of Pearl, and the videotaped beheading of his victim — is the essence of the film. On the one hand, a Jewish-American reporter who (in the words of HBO’s press release) tried “to promote cross-cultural understanding,” kept a picture of Ayatollah Khomeini in his cubicle, and was affectionately dubbed “Danny of Arabia” by colleagues; on the other, a Muslim Englishman, educated at the London School of Economics (“a model English gentleman, as it were,” a teacher recalls), who already had cross-cultural understanding and, one is tempted to say, became extremely cross as a result of it.

Or as the press release puts it, “Sheikh was radicalized by events that he regarded as the global persecution of Muslims, and became an Islamic militant who chose a deeply violent method to achieve what he believed in.”

An FBI agent sent to Karachi after Pearl’s kidnapping is less diplomatic. Of Sheikh, she says: “He’s an intelligent man. I mean, he’s very well educated, a smart man — but a psycho.”

Narrated by Christiane Amanpour, “The Journalist and the Jihadi” begins by sketching some of the events that preceded September 11, 2001. (Almost two decades on, the sight of Muslim mobs burning Salman Rushdie’s “The Satanic Verses” in London is an eye-opener.) We also see home movies of Pearl’s idyllic childhood in Encino, Calif. — today would have been his 43rd birthday — and track the growing interest in journalism that eventually brought him to the Southeast Asia desk of the Wall Street Journal.

Sheikh is recalled almost entirely in flattering terms by professors, school chums, and arm-wrestling opponents. (He was an ardent arm-wrestler, as videos of him taking on men twice his size in London pubs demonstrate, as well as a junior chess champion.) He seemed destined for success until he was supposedly transformed by the massacre of Muslims in Bosnia. That Americans, not Europeans, put a stop to the carnage is a fact he conveniently ignored. One wonders to what extent the rote anti-Americanism of British academia, even during the Clinton era, also affected his thinking.

“The Journalist and the Jihadi” has its share of dramatic re-enactments, but there’s a key scene from which it wisely shies away, since only a novelist (or a screenwriter; two feature films about the Pearl case are in production) could do it justice: The initial meeting between the two men. Although Pearl was a reporter for one of America’s most famous newspapers, Sheikh, as comfortable in the First World as he was in the Third, probably considered the American a naif who was out of his depth. His ability to win Pearl’s trust must have given him a great deal of perverse pleasure.

The deadly pas-de-deux between the two men began because Pearl, trying to tease out the financing behind September 11 and the role Pakistan’s secret service may have played in it, wanted to interview Sheikh Mubarak Ali Shah Gilani, a Brooklyn-based imam who fled to Pakistan in 1993 after one of his followers was implicated in that year’s attack on the World Trade Center. Pearl was apparently convinced that Gilani’s organization, Al-Fuqrah, was connected to the September 11 plot. Sensing an opportunity for mischief, Sheikh, using the alias “Bashir,” contacted Pearl and offered to put him in touch with the elusive imam. Although Sheikh masterminded the kidnapping, Pearl was probably executed by Khalid Sheikh Mohammed, now in American custody but then the number three man in Al Qaeda.

Far from ending up as a “universal person,” Pearl was probably killed simply for being an American and a Jew. Another theory is that Sheikh kidnapped him in an attempt to embarrass and possibly even topple the government of Pervez Musharraf. Bernard-Henri Lévy, the author of “Who Killed Daniel Pearl?,” believes Pearl may have been murdered because of something he discovered about the plot behind September 11, but there is no real evidence to support this; the FBI itself felt Pearl was on the wrong trail. Sadly, it appears he was not the man who knew too much, but too little.

Some of the most remarkable footage in this film, directed and produced by Ahmed A. Jamal and Ramesh Sharma, is of Karachi, a heavily guarded city in southern Pakistan with a population of 14 million people, all of whom appear to be male. (The contrast with urban Iran, also filmed, where black-clad women carry themselves with an air of dauntingly severe chic, is striking.) It was in Karachi that Pearl was kidnapped, and one can only conclude from what is shown of this wild-looking place that he had an almost impossible job trying to make sense of it.

If this fascinating documentary has a weakness, it’s that it tries to tell the story of Pearl’s death and its aftermath while doing double duty as an homage to Pearl himself. (At 80 minutes, there isn’t enough time.) Nonetheless, it’s impossible not to be moved by the revelation that his mother, asleep in Encino at 7:20 a.m., had a nightmare that her son was in trouble (she got up and sent him an email immediately) as he was being kidnapped at 8:20 p.m. in Karachi.

Likewise, when Asra Nomani, a Muslim colleague of Pearl’s from the Journal, relates how she fervently recited a Muslim prayer on learning of her friend’s death, one feels a sliver of hope for the interfaith understanding the Daniel Pearl Foundation is dedicated to promoting.

As for Sheikh, still alive four years after being sentenced to death along with three accomplices by a Pakistani anti-terrorism court, his justification for luring Pearl to his death is unambiguous: “Jihad.”