This album has been about in virtual form since last autumn but now receives physical release. In more ways than one. Since theartsdesk didn’t review it back then, its reappearance on CD and vinyl gives us an excuse to now. After all, Swedish musician Karin Dreijer – once of The Knife – is fascinating, an artist who pushes at the boundaries. She revived her Fever Ray persona last year amidst videos revelling in sci-fi weirdness and orgiastic BDSM imagery. Plunge is the musical life statement that follows.

Five years ago Dreijer divorced, shaking off the “Andersson” that once double-barrelled her name. She has since been exploring her mostly gay sexuality in an untrammelled physical manner, according to both interviews she’s given and the lyrics here. Where Fever Ray’s eponymous debut album, nine years ago, was morose, the sound of a woman trapped, depressed even, by parenthood, Plunge is an explosive liberation. With it comes a twisted electro-pop that upon occasion, as on the celebratory “To the Moon and Back”, is even light and accessibly melodic.

That’s not to say this is all easy stuff. On “Falling” she seems to be exploring her sexual identity via a chugging Gary Numan-esque machine rhythm, while the techno pulsing “IDK About You”, with its occasional orgasmic yelp samples, may be about Tinder hook-ups and trust. The true centrepiece and manifesto, though, is “This Country”, which stridently identifies sexual repression with political will. Many will turn to the line “The perverts define my fuck history” but, perhaps, it’s true core lies in the couplet “Free abortions and clean water/Destroy nuclear, destroy boring”.

Plunge is less art-obtuse than much Dreijer has been involved in, closer in tone to Björk and, musically, Santigold’s underheard 2016 album 99¢. She remains her own creature, not releasing this through commercial imperative but as a necessary proclamation, yet it’s as pop as anything she’s done since The Knife’s second album 12 years ago.

• Read more new music reviews on theartsdesk

Overleaf: Watch the video for "To the Moon and Back" by Fever Ray

Sara Lund and Saga Norén have a lot to answer for. Their adventures in the murk of murder as they grapple with their own dysfunctional psychology entranced audiences who don’t speak a scrap of Danish or Swedish. The search has since gone on for other gripping instances of Nordic noir. How long can it be before we accept that The Killing and The Bridge both had ingredients that aren’t easily reassembled?

The new import is the latest procedural from Scandinavia, this time focusing on Stockholm’s biker gangs. The first episode aired Tuesday night, with the rest of the series available on All4 now.

You haven't lived until you've witnessed Viennese maverick H(einz) K(arl) Gruber – 75 today (3 January, publication day) – speech-singing, conducting and kazooing his way through his self-styled "pandemonium" Frankenstein!!. Composed for chansonnier and chamber ensemble or large orchestra, it's a contemporary classic nearly 40 years young.

Even given the peerless standards already set by Sakari Oramo and the BBC Symphony Orchestra in their Sibelius cycle, this instalment was always going to be the toughest, featuring the most elusive of the symphonies, the Sixth, and the sparest, the Fourth. As it turned out, all challenges were met with Oramo's characteristic mix of energy and sophistication, and the interloper, Swedish composer Anders Hillborg's Second Violin Concerto in its UK premiere, saw to it that Lisa Batiashvili carried the flame.

Was it going to be generic contemporary? The skeetering strings at the beginning suggested as much. But their headlong collision with a chorus of sustained chords proved arresting: what sounded like a pre-recorded ambience turned out to be those same strings turned to calm seas. In effect much of the one-movement concerto was searing cadenza from the compellingly intense Batiashvili (pictured below with Hillborg, Oramo and members of the BBC Symphony Orchestra by Mark Allen), mostly accompanied until close to the end and punctuated by two wild eastern dances – part Turkish sanat, part Bollywood, with Hillborg making and needing no apologies for the populism.

The intensity held; the ear was led through ever-unexpected harmonic shifts, and where the work might have sagged, the two oboes and cor anglais introduced a mesmerising new hook. Filmic in effect, but never merely film music. Given the echo of Bach's D minor Sarabande near the start, the ethereal encore was entirely appropriate – Hillborg's arrangement for violin and strings of the organ prelude on the chorale "Ich ruf zu Dir".Well might any contemporary composer quake about sharing a programme with Sibelius, whose originality in the best performances always makes his music sound as if were composed yesterday. And these interpretations were indeed the best. Oramo knew he could draw maximum, dynamically nuanced soulfulness from the BBCSO strings in the profoundly beautiful hymns which frame the work – the last, dying out on a single note, is as convincing an ending as Sibelius ever wrote, making this more than ever a candidate for the end rather than the beginning of the programme (as usual, alas, it appeared in the first half). So did the muscular energy of the outer movement's strange adventures and the Beethoven-like primal charge of the scherzo, bursting straight out of the Allegretto moderato's twilight zone. The sudden flautato semiquavers which quicken its pulse with quiet intensity, backing quirky snatches of birdsong, are a test for any conductor; all credit to Oramo and the BBCSO that those forest murmurs have never sounded more compelling.

Though the Fourth could hardly be further away in its slow-evolving dark power, the hallmarks of these interpretations remained: the powerfully-vocalised wind solos (flautist Michael Cox especially impressive), the simultaneous projection of upper, middle and bass layers, all doing their own distinctive thing, and the way Oramo sustains a line or an argument even when it's punctuated by long silences. The high watershed both of Sibelius's unique tragedy among his symphonies and of the playing came in the great slow movement, heroically trying to piece itself together out of numb, depressive fragments. It's the cellos who finally, gradually manage to give full voice to a cathartic lament. That climb of theirs out of the darkness last night will stay with me for ever.

• Listen to this concert for the next month on the BBC iPlayer
• Read more classical reviews on theartsdesk

Next page: watch Lisa Batiashvili with Sakari Oramo conducting the Royal Stockholm Philharmonic in the 2016 premiere of Hillborg's Second Violin Concerto