Ah, Sons and Daughters – they grow up so fast. Decidedly upbeat in places, 2008's Bernard Butler-produced This Gift seemed to be the sound of the Glasgow quartet making a break for the mainstream, with Motown inflections, a song with a chorus that went "na na na" and a unusually high percentage of major chords. But that record's wonderful opener, 'Gilt Complex', without doubt their most catchy and polished tune, didn’t bring in the gold chart-wise, though it did find its way into an advert for rugged hiking boots – and it's not unenjoyable to picture their manager breaking the news: "Guys, Timbaland's on the phone and he says he loved the record! What's that? Timberland the shoe manufacturer? Oh. Oh right."

Anyway. The tone of fourth album Mirror Mirror is perhaps a tacit acknowledgement that a band so fixated on singing about that classic cause of relationship break-up – we're talking about cold, bloody murder, of course – is not destined for the glories of the hit parade alongside yer Jessie Js, and so might as well get on with producing "mature and challenging" work. Reading between the lines a little, the fact that Mirror Mirror's press release claims the quartet took their first (mini) album (2003's Love the Cup) and second (2005's The Repulsion Box) as inspiration sounds like there's a wee bit of disavowal going on. Just no one tell Bernard, all right?

This time it's Glasgow legend JD 'Optimo' Twitch at the producing helm and mesmerising opener 'Silver Spell' casts him as an interesting force: out goes the indie-punk guitar template and in comes the pickaxe drumbeats, piston percussion and leaden synths, which hammer away while Adele Bethel and Scott Paterson chant out some kind of incantation, threatening: "Don't touch the cracks too much / Your eyes will sink to floods." It's Alan Garner meets The Human League and probably the most curious thing they've done.

That said, it's something of false indicator, since things get more conventional from thereon in. The sound is still very stripped down and white noise is splashed around with care, but there's still the old tightness and sharp sense of rhythm, where the bass seems to be beating out time just as much as the drumbeat. 'Breaking Fun', the single, is Bis dosed up on PiL, all padding bassline and swooping singing from Paterson. 'Don't Look Now' is filled with disembodied yells and screechy avalanches pulled sharply back into line by metal-like riffs, power drills and the barking of electronic dogs (although no psychotic dwarfs in red coats, sadly). 'Bee Song' swivels on a distinctly Radiohead-like groove overlaid with a beautifully breathy Bethel vocal and a buzzing bee backing chorus, like she's whispering her message while sheltering from the swarm.

Kills 'n' thrills all round, then, but there are a few bellyaches: 'Orion' is plodding and unremarkable, while 'Don't Look Now', for all its sonic usefulness, does go on a bit (particularly for a band who specialise in brevity). 'Ink Free' is nearly marvellous, but features some curiously vapid and off-key singing, as if everyone was so rapt by the sounds of the typewriter that clatters out the beat between verses, they forgot to do a second take.

The band are at their most exceptional when the going gets dark. Serial killer rocker 'Rose Red' is shot through with a bass hook bordering on surf rock (though the Bermuda shorts have presumably been ditched for long black coats), but begins with the unsettling line: "Played you like an organ in a granite chamber..." and finishes with some fantastical axeing and shredding (of guitars, you'll be relieved to hear), Bethell having made good her escape, crowing: "I've left no trace, try to find me, I'm cocksure".

Like a Dexter boxset with "Play All" selected, we're straight into another grisly but gripping episode in the form of 'Axed Actor', which tells the story of youthful 1950s starlet Elisabeth Short, who became known as the Black Dahlia after being murdered in horrific fashion. "The last ever picture show," croons Bethell as Paterson caterwauls in the background like an injured Morrissey. "Cut into pieces, switchblade smile across your face". The Glasgow smile, that's how it goes round Sons and Daughters' way. We can't imagine the folks from Timberland will be calling back any time soon.