Named after a documentary about a Japanese biker gang, Godspeed You! Black Emperor fulfil a role in popular music akin to that of Chicken Little or the ancient Greek prophetess Cassandra, a seer whose doomy foresights came with the curse of being disbelieved. Punk rock in spirit if not in sound, the Canadian instrumental ensemble have steadfastly channelled doom, joy, gallows humour and a excoriating critique of modern times off and on since.