In the mystery-o-meter rankings, with well over a decade of experimental and provocative electronica to their name, The Knife have long since occupied a spot alongside enigmatic and unconventional musicians and producers such as MF Doom, Daft Punk and Aphex Twin.

Summarising the Swedish duo’s output beyond that description is a little tougher. Their 2001 self-titled album, 2003's Deep Cuts, 2006's Silent Shout, the Fever Ray record by one half of the band, and operatic work Tomorrow, In A Year are a mix of all-consuming and painfully beautiful creations, each subtly different from the last.

Up until the point of researching for this write-up, I knew very little about Karin Dreijer Andersson and her younger brother Olof Dreijer. I'd deliberately kept my distance from the noise surrounding their new release over the past few weeks, partly because I didn’t want to prejudice my review until it was written, but mostly because I wanted to keep the relationship I have with this band intact and limited to the eccentricities of their music: a schizophrenic mix of cryptic and overt lyrics delivered though sweet, kooky and occasionally demonic vocals, set against unpredictable arrangements of dark and brooding IDM.

As it happens, I wouldn’t have found out too much about them had I looked prior to the release of Shaking The Habitual, their first studio album together in seven years. In the past, both artists have been carefully secretive about their projects and live appearances whether together or solo, keeping contact with the media and live shows to an absolute minimum. Maybe something has changed during the three years of working on this album, as recent features in Spin, Pitchfork, The Guardian, Dazed and fifteen-odd other interviews would suggest.

Such new found openness may well have been influenced by the experience of collaborating with Mt. Sims and Planningtorock to produce Tomorrow, In A Year, 2010's avant-garde opera based around the life and work of Charles Darwin.

For a start, there's length. Previously, The Knife's longest song came in at just over seven minutes, with most averaging around four. At 98 minutes duration, Shaking The Habitual is longform by comparison, with eight of the thirteen tracks six minutes or more in length, including one monster that clocks up at 19:22.

This bigger aural canvas means less structure and more space for experimentation, as demonstrated by the other-worldly dronescape of 'A Cherry On Top', made up of countless layers and samples which rise and fall with siren-like frequency. The futuristic profundity of the near twenty minute electro-acoustic trek 'Old Dreams Waiting To Be Realized', along with 'Fracking Fluid Injection' and the Margaret Attwood-inspired shorts 'Crake' and 'Oryx', also represent this departure from the norm – if such a thing exists for both artists – though the dark overtones found in most of their work to date are still present, helping to anchor the album to something of a familiar feel and flow.

Similarly, the strong drum patterns and percussion which have underwritten much of the sibling's music in the past, such as the electropunk kicks and claps on older tracks like 'You Take My Breath Away', 'Marble House' and 'Like A Pen' haven't been lost - the distorted punches on 'Full of Fire', tribal toms and tight snares in 'Without You My Life Would Be Boring', and staccato percussive samples on 'A Tooth For An Eye' and 'Ready To Lose' are all pure Knife, and the album certainly benefits from the consistency.

Plenty of other parallels and contrasts are dotted throughout the album too: the striking 'Raging Lung' sits at the confluence of trip-hop and deep electro, with low husky verses and reverbed choruses over searing industrial noises and the harsh reverberations of horsehair scraping metal, whilst conversely, 'Full of Fire' and 'Networking' are fast Miss Kittin style technopop numbers featuring bursts of percussive IDM drill-like samples and loops, bolder and brasher tracks more in line with Deep Cut's 'Listen Now' than say the more subdued work on Silent Shout.

And as I've now found, the duo's beliefs - particularly on this album – ranging from topics such as queer politics, imperialist governments, gender inequalities and extreme wealth, and their longer-term influences like David Lynch, Jeanette Winterson, Richard Kelly, Judith Butler, Kate Bush and Le Tigre, are more explicitly scattered throughout their music, whether lyrically or instrumentally, than ever before. Political statements, unusual samples, subversive messaging, synthpop melody lines and brusque fade-outs all sit alongside together as if non-conformity were the most natural thing in the world for The Knife.

The shadowy aesthetic of Karin Dreijer Andersson's vocals is at the absolute centre of most of the tracks, whether of pleading and desirous style on songs like 'A Tooth For An Eye' and 'Wrap Your Arms Around Me', pitch-shifted and manipulated almost to the point of being unintelligible as in 'Full Of Fire', or straight sung against Olof's ('Stay Out Here'), simultaneously frightening and soothing, in the same vein as early Bjork material and CocoRosie's astonishing creations.

The sister and brother duo have succeeded in delivering a record that is as powerful and captivating as any of their previous, the charge of Deep Cuts, the complexity of Silent Shout and the challenging forms, shapes and concepts of Tomorrow, In A Day all being here, in one way or another. Shaking The Habitual is a collection of many characters, each offering a different immersive and dazzling interaction. Still unconventional and still brilliant, The Knife may be sharing more with us than ever before, but you can't help but feel there is so much left to discover. Sheer genius.