CocoRosie make no concessions to the mainstream. If their album cover, which depicts them moustachio’d and felt-hatted behind Comic San’s evil twin of a font (very arguably an improvement on copulating unicorns) wasn’t enough to deter you, they describe the album’s genesis as, amongst other things, ‘journeying inward, into the forest-dark ember, led by crystal light, the voicing of whales and ancient souls passed’. Uh, sure. But persevere beyond this airy-fairy eccentricity and there’s an album so good it threatens to push them into the limelight.

Grey Oceans, half recorded with a renowned engineer in Buenos Aires, half all around the world, manages a similar balance between ranging widely and wildly and being anchored in something coherent. As well as the more polished production, there’s a subtly drowsy, elegiac tone that runs through it. Perhaps it’s something to do with the change of label (Sub Pop) and new member Gael Rakotondrabe, with whom they claim an ‘explosive alchemy in collaborative song writing’.

Evidently there is something slightly magic going on. CocoRosie were good before, but now their exotic, unique charm is tempered with songwriting maturity. Grey Oceans gathers influences and instruments – nursery rhymes, electronica, choral music, hip hop, Indian strings, even a sample of their mother singing in Cherokee on the mournful, mumbled ‘Undertaker’ – into well-crafted, intensely evocative songs.

Picking highlights is difficult. In ‘Smokey Taboo’, Bianca chants over a trance-like tabla, singing of sirens you can vaguely hear in intermittent squalls of sound, and all the while haunted by her sister’s beautiful refrain. CocoRosie excel at creating atmospheres you can almost feel, like the too-hot summer of ‘Lemonade’s lazy, sultry, pop or the twisted fairy-tale gloaming of ‘The Moon Asked the Crow’. The title track, a languid, melancholy masterpiece of hymn-book chords and echo-chamber vocals, demands a cathedral to do it justice.

That’s not to say there are no low points. Whether you think Bianca’s rasp is more endearingly affected child or warbling hag will definitely affect your enjoyment, especially in ‘Hopscotch Teardrop’ which, to my mind, begins with an ear-severingly irritating refrain of inane faux-childish jauntiness, until, thankfully, it’s ambushed by a skittering beat and submerged in a giddy, disorientating mist of electronica.

But CocoRosie will always have this side too, like their two voices, and the contrast generally works well. Likewise, though the lyrics occasionally daydream into nonsense, mostly they mix sinister folk-tale imagery with a touch of impish lightness – take ‘RIP Burn Face’ where the acid-burned heroine drowns herself “sunken with her party balloons”. In a word: enchanting.