Humanising the inhuman but never ever justifying, Path of Blood directed by Jonathan Hacker is a documentary that attempts to open up the beating, bloody heart of Al Qaeda between 2003 and 2009.

Based on his book of the same name Hacker delves into Islamist terrorism through hundreds of hours of tapes that Al Qaeda’s own followers shot, as well as CSI footage from the Saudi Arabian police that recorded the results of their outrages.

At times its chilling in its banality as the terrorists record their suicide messages so inept that it takes them several attempts before they get it right. The training camps that have the appearance office awaydays and bonding sessions only they are learning about bombs and Kalashnikovs. On the way to their missions they look as if they are on a jolly. It appears absurd, totally bizarre which the film then throws into the sharp light of the atrocities.

The capture, torture and murder of an American is dreadful and harrowing. There’s no footage but the sounds are enough as we hear him struggle and the kidnappers ask for a knife. The firefight when the terrorists are cornered in a town and a three-day siege, and the black and white images of vehicles as they attack an oil refinery, murdering three guards but failing in their mission.

The footage of the aftermath of attacks are bald. The blood on walls of a failed assassination attempt, and limbs and body parts strewn everywhere.

Path of Blood is an intense and harrowing experience that doesn’t hold back and is the better for it. The film is carefully edited though straight down the line with a narration by Samuel West but not a commentary and no interviews. Tom Hollander is the terse ‘Voice of Jihad’. It’s the images and their own words that bare the fanaticism of the terrorists, as they play with children in hoods and in their conversations as they drive towards their targets, and deaths.