It’s a shame that HBO’s sporadically riveting movie “Dirty War” doesn’t dare to be subtle. The gripping premise – a terrorist attack on London, a city not properly prepared for one – works on a New Yorker in ways even residents of London might not have experienced from this overly straightforward British production. From the superb reporting of Kevin Flynn and Jim Dwyer in their new book, “102 Minutes,” we now know just how poorly our city’s emergency services were prepared for the World Trade Center attacks, and to what extent that weakness contributed to that day’s devastating death count. The notion that a major urban center can be devastated without warning is no longer an implausible fiction.

It is from that sad truth that “Dirty War” draws its point of view – a noble impulse. The result is an important film worth watching despite its flaws. From its opening scene of a terrorist-attack drill, in which firefighters discover just how likely they might be to die in the event of a real dirty bomb attack, there’s never any doubt where “Dirty War” is headed, but it’s still impossible to look away. Yes, we can see the wheels turning at every moment, and we know that the attack we’ve just seen played out in a drill will soon be re-enacted in reality, but its predictable approach makes it no less gruesome. The battles among bureaucrats seem chilling when refracted through the experience of the eventual bomb attack that gives this movie its before-and-after structure.

The essential conflict at the core of “Dirty War” is between those who truly understood the threat that became reality and those who falsely convinced themselves they were ready for it. Nicola Painswick is the new minister for Lon don, who argues strenuously throughout the movie’s first half that her city has adequately prepared itself for the possibility of a terrorist attack. She goes around London testifying to committees and addressing conferences about her expectations for success, in the process annoying those who know better. At one point she’s confronted by Murray Corrigan, a firefighter who helped lead the drill in the opening sequence, and who argues with her about the city’s preparations. “London is now better prepared than it has ever been,” Painswick declares. He glares at her and replies, “Were you at the same drill I was?” Two firefighters at the drill had their suits torn in a manner that in a real attack might have resulted in their death.

Meanwhile, a Jordanian is preparing just such an attack, assembling radioactive material to be detonated by suicide bombers. He runs a cell with Pakistanis from a dingy safe house. The tension mounts as bureaucrats combing through documents begin to get hints of the threat from suspicious neighbors, but by the time they engineer a raid, it’s too late; the attack is nearly underway. The suicide bombers explode their load in the middle of morning rush hour, in a devastating sequence that results in dozens of deaths and a radioactive cloud hovering over downtown London. It’s a brutally realistic sequence that gives the movie a documentary feel; had it not been so utterly expected by that point, its impact might have been even more powerful. What we learn in the aftermath of the attack is the most obvious of lessons: the naysayers were right. London wasn’t ready.

This co-production with the BBC has its moments, most of them in the second half. The bombing sequence itself has a harrowing aspect, with surveillance cameras searching desperately for signs that more suicide bombers are waiting to attack. The off-screen experts rattling off the names of radioactive gases in the air are terrifying. It’s hard not to imagine how such an event would play out on New York’s streets – or to wonder whether our city is any better prepared today than it was on the morning of September 11, when thousands died. There’s no doubt the producers of “Dirty War” intended to scare us with their documentary-style approach to this horrible scenario; that they succeeded may be seen by some as exploitative and wrong-headed. But maybe it takes this kind of in-your-face filmmaking to wake up those responsible for our well-being. It may not be sophisticated storytelling, but if “Dirty War” reminds a single public safety official of the permanent threat of radioactive danger we face, it’s done some good.

***

Among the more mystifying developments in recent months was last Sunday’s Golden Globe award for best actress in a drama, given to Mariska Hargitay, the co-star of “Law & Order: Special Victims Unit.” Ms. Hargitay won for her portrayal of Detective Olivia Benson, who is perhaps television’s dullest detective – and remember, that list includes David Caruso in “CSI: Miami.”

There are legitimate concerns about Ms. Hargitay that the Golden Globe voters have, in my opinion, blithely overlooked. For one thing, she looks perpetually confused by the convoluted plots, and she always seems vaguely embarrassed to be talking so regularly about sex, even though that’s the basis of virtually every crime investigated on “S.V.U.” Nor am I particularly fond of Ms. Hargitay’s nasal monotone. I also disapprove of her predilection for brown pantsuits. And, let’s face it, her name looks like the starting clue to a New York Post word jumble. Is this a deserving Golden Globe winner? I think not.