A caustically intense mainstay of the US underground, Thou combine cavernously sludgy riffs with raw punk energy. Theirs is a sound of stifling humidity, a near hallucinatory heaviosity. Indeed, the narcotic heat of Louisiana – the band are from Baton Rouge – seeps through every sickly pore, wedding itself to the circling riffs, loose rhythmic under-swing and throat shredding screams alike: a brutal urban blues.

But where 2014’s breakthrough Heathen was of a more epic, doomy bent, Umbilical – the band’s sixth full length album – speaks more closely to Thou’s links to the underground punk and hardcore scenes with shorter, (even) more aggressive songs and in-your-face delivery. Working up a vast – at times overwhelming – wall of sound, Emotional Terrorist and Unbidden Guest rage along with fearsome intent while The Promise is brutally off-kilter. I Return As Chained and Bound to You and album closer Siege Perilous, meanwhile, are lumbering sludge classicism.

Bryan Funck’s serrated, guttural vocals prove surprisingly limber throughout, while guitarists Andy Gibbs, Matthew Thudium and KC Stafford trade riffs by turns crunchy and rolling, a pleasingly neanderthal groove ever present. In a recent interview, the band talked about Umbilical as an exercise in self-reflection, taking stock of whether they’ve measured up to the self-imposed DIY ethics the outspokenly leftist band set themselves from the start.

What results is the most maximalist and invigoratingly cathartic exercise in introspection you could possibly imagine – and one of the finest metal albums of the past decade.