I'm commuting in and out of work everyday, thanks to the location of my new flat. It's odd to feel apprehensive when it's time to go home, and I never really relax on the tube. These feelings are not particularly rational. When people say that statistically the chances of being murdered on the Underground are very small (although not so small as winning the lottery) they are, of course correct. Despite this, I feel uneasy, like many people. I look around for potential bombers (as if spotting them would do any good). I feel relieved when I step off the train. Logically, it's insane, but I just can't help it. Nor can a lot of other Londoners if various website and blog comments are anything to go by.

So it wasn't especially helpful for LoveFilm to mail me 9/11 the other day. And it wasn't especially helpful for me to feed it into the DVD player and settle down to watch it yesterday evening.

Back in 2001, filmmakers Jules and Gedeon Naudet were shooting a fly-on-the-wall documentary in a downtown Manhattan fire station. Early on 11 September the camera followed some firefighters responding to a report of a gas leak. As the firemen wave their odd looking gas detector gadget over a grating in the pavement, the sound of a plane causes them to look up briefly before returning to their work. The camera however finds the plane, and follows it into the side of one of the towers of the World Trade centre. The footage is one of only two known images of the first plane crashing into the building. The film goes on to record the events of the next few hours - one camera is on the streets, the other inside the WTC.

The film is refreshingly unpoliticised (limited more or less to one fireman muttering "son-of-a-bitch" at George W. Bush) and free from religious commentary. Any patriotism is also pleasantly muted (by American standards). It is simple reportage. I found the film profoundly affecting. The ability of those images, which we no longer see on the television, to astound and horrify with almost the same impact as four years ago surprised me. They are also a chilling reminder of the lengths to which some will go, gripped by vicious faith in their actions and an unshakeable belief that they are right.