And with that, it begins.

Nucleus' second release, the enigmatically-titled Circumvolution EP is intensely dark, ebbing and flowing for its entirity.

"Epic Song", the introductory track, is fast and furious. Matthew Quayle's vocals are a highlight, with great harmonies and vocal doubling used to craft a call-and-response effect on the verses, contrasting with clean singing on alternate lyrical lines.

Almost inaudible voice samples and keyboards add an extra layer to the sound, and its clear that to fully take the EP in you need to listen to it with headphones. A lot of effort must have gone into developing each song into more than just a collection of riffs and melodies, with each track possessing its own subtle layer of electronics and effects which, though easy to miss, give each song a unique flavour.

"Epic Song" contains a thread of middle-eastern influence which is bound together in the creepily discordant oud solo which breaks up the middle of the song; it is this polish that elevates Circumvolution to something more than the sum of its parts.

The thread running through the second track, "Orion", is a computerised, digitised effect on a lot of the vocals and in a keyboard line way down in the mix. Down-tuned, angular guitar riffs and a wandering, rolling bass line contrast with the choral sound of the vocals, which are softened by an interesting production technique where each line is preceeded by a reversed voice sample, which cushions the first syllable of each line and gives each one a dream-like surrealism.

Electronics and discordant beeps and bloops also flow through "Solitaire Reaction", though it is much slower and bass-heavy than the previous track, with Ayden Mitrovich's melodic bass lines shining. From each verse and chorus to another, the song shrinks and grows, building in intensity, before flurried drums rolls and passionate, Maynard-esque screams bring the track to an epic and sudden close.

Out of the silence, a bass line reminiscent of Dream Theater's "Home", awash in atmospheric keyboards, rings out. Brooding, almost whispered vocals and a middle-eastern guitar sound take centre stage, before positively exploding into the chorus. At times, "Pirates" is the heaviest song on the EP, and offers the best of many opportunities for headbanging, descending into full-blown heavy metal during the final verse.

But during the more crowded sections, one of my main criticisms of the EP becomes evident: the mix has a tendency to become muddy when the sound is at its fullest, and it can be difficult to distinguish different sounds. The sound quality is nothing short of remarkable at times, especially with regards to the numerous and varied effects, but during the heavier sections its easy to feel suffocated.

But, as with the rest of the record, it doesn't linger in the same place for long, and the final minute of the song is surprisingly calm. The transition into "Paragon" begins unassumingly with a lone cello, once again ever-so-slightly manipulated to provoke a feeling of uneasiness (this cello sounds like it was recorded in an empty hall 70 years ago). Swimming in a distant sea of droning guitar, the song slowly meanders its way through its winding path, with the occasional sprinkling of piano lending it a distinct post-rock flavour.

Nucleus acknowledge the influence that Massive Attack had on their music by covering "Dissolved Girl" to bring their EP to a close, and as far as covers go it is very faithful to the original other than the obvious masculinity of the vocals. Surprisingly, this is one of the least electronically-affected songs on Circumvolution, though it does recreate the metronomic electric drum sound of the original, and like the Massive Attack version fades out to bring the record an understated close.

Circumvolution is an absolute must-have for any Australian music lover. Metal fans will love the sheer mass of the guitar and bass, trip-hoppers and post-rock fans will love the depth of the keyboards and the atmospheric side, and prog fans will love the contrast between the two.

The blending of these two often-coupled extremes is not ground-breaking, but in this case it is certainly exceptional. The darkness, intensity, and lack of solos bear passing similarity to Tool, but if the atmospheric side of their music is further developed, Nucleus could become true heavyweights of the Australian heavy rock scene.

Circumvolution is available to buy from Nucleus' MySpace profile at www.myspace.com/nucleusband.