Neko Case remains surprisingly unknown in some quarters. At least, it’s surprising given her gift of a voice – an alt-country spine-tingler, full of nuance and a curious combination of wisdom and innocence, that could give the greats a run for their money. It’s less surprising given the ends to which she applies it – deep, rich, complex albums like this whose appeal is satisfyingly unstraightforward. Even after multiple listens to Hell-On, you feel like you’re only beginning to get a handle on it. In the best of old-fashioned ways, this is an album that rewards the time you put into it.

Not that Case is incapable of plain tunesmithery when called to it. Bad Luck is the simple pleasure on which the album’s mass marketing depends, a straight verse-chorus that’s almost Radio 2 in its sensibilities. To these ears, it’s too straight, but then most albums need their instant kicks.

It’s the only instant hit you’re getting on this album, though. That much is obvious from the get-go, when a spooky honky-tonk music box introduces the opening title track, and Case hits the listener with terse theology: “God is not a contract… [beat]… or a guy.”

It’s a fair representative of the best of Case’s work – enigmatic, anachronistic, and stylistically tapping into both the folk horror of the American backwoods and European art song.

But then what’s this? Last Lion of Albion? American alt-rock star pens love song to Farage? If anything, it’s the opposite. It appears to be a song mocking national pride before a fall, about exhausted nature bringing about the end of days. “They’ll use you for centuries to come,” she sings, with the end of a civilisation hanging in the air. “You’ll face extinction” like the “last she-wolf to mother Rome”.

Man’s misuse of nature also becomes metaphor on Halls of Sarah. In a vocal that sounds ever so slightly auto-tuned, Case sings of womanhood mistreated, allegorically at first: “A childless widow of the nation… yet we expect you to bring springtime” before being more explicit about “loving womankind as lions love Christians”. Mood-wise it’s a distant cousin to Fleetwood Mac’s Sara.

Mark Lanegan fetches up as vocal partner on Curse of the I-5 Corridor, as distinctive a voice as there is in modern rock music, and so over-used as gravelly counterpoint, it reduces what could be a fascinating piece to same-old, same-old, especially as all he’s doing is following the same melody line. It’s much better when the vocals drop out and the instruments are allowed to roll and tumble to their end.

A similar criticism can be made of Sleep All Summer, her duet with Eric Bachmann of her backing band. It’s his song, a perfectly pleasant slab of bright Americana on which both ask: “Why won’t you fall back in love with me?” But it’s disruptive of the mood. Like Lanegan’s contibution, it adds little to the album.

Mid-album trio Gumball Blue, Dirty Diamond and Oracle of The Maritimes combine melody, melancholy and musical texture with an ease and artistry reminiscent of R.E.M. or Nick Cave at their free-flowing best. Like Cave, she’s not afraid to pierce her oblique poetry with earthier banalities either. “I’m not even wearing underwear,” she sings on Oracle. “In no way exotic, I just forgot to.”

Winnie enables her to stretch her country side, while My Uncle’s Navy is a mid-paced FM rocker, a subdued sibling to Dire Straits’ So Far Away, until it drops out for Case to intone, like a dark nursery rhyme, “black is blue, if I say it is”. It’s another example of how she can derail and take a detour mid-song, abandoning conventional structural signposts. Closer Pitch & Honey relies on lo-fi bobbling beats until gradually evolving into something more conventional.

At its best, Hell-On shows what exquisite pieces can still be forged from traditional folk/rock/country idioms. Nothing here has been heard before and the craft is there to see for anyone who spends the time on it. In the end, though, that’s also the thing holding the album back. Far more than the intrusive guest vocalists, it’s the sense that each piece has been carved separately from the others which takes the shine off. Nothing binds these into a whole. Case has created a series of beautiful artefacts, but placed them around the gallery in such a way that it’s hard to appreciate the shared context.