BEWARE A rush to judgement on any Plague Monkeys recording – here be sleepers. Last year’s debut Surface Tension pleasantly perturbed this candidate on the first to fourth helpings, but by the dozenth dose I was figuring it for a minor classic. Even now, it still yields sheathed details, peculiar possibilities.

So, your reporter approached The Sunburn Index with both relish and caution, although any fears of the quartet grafting a big ugly fuck-off backbeat or radio-friendly sheen onto the sound are almost instantly dispelled – all loops remain self-generated, all samples plucked from their own manuscripts rather than public libraries.

Again, it’s the invisible ink encoded in the sound that works its way into the listener’s bloodstream, tattooing the brain many hours later. And, as you may have deduced from the titles, the lyrics continue to probe the sciences, and indeed the virus of language itself (“What Americans call ‘closure’”) in the quest for a dialect new to rock ’n’ roll.

The band’s vocal point is of course Carol Keogh, a spellbinding warbler who has inherited Mary Margaret O’Hara and the Buckleys’ knack of springing words loose from meaning. Throughout this collection, Keogh performs all manner of tonsil somersaults while remaining firmly integrated into a band who know just how tightly to boa-constrict her throat. Donal O’Mahony is particularly adept at framing the melodies with a succession of electric/acoustic backdrops (indeed, he gets downright industrial during the penny-dreadful peekshow of ‘Over’), while on ‘Sea Change (Part 2)’ Barry Roden and Thomas Haugh – surely one of the more underrated and imaginative rhythm sections in the parish – shape-shift like salamanders, performing acts of enviable sonic contortion.

I have one or two faint misgivings – considering the magic these Monkeys are capable of working with conventional song structure (‘Bloomsday’) one sometimes gets frustrated by their adherence to initially opaque surfaces. In other words, I don’t hear a single. And occasionally there are hints of late 80s student ghetto-ism – Throwing Muses, The Cocteau Twins et al – which you suspect mask a latent ability to get as crossed-over as Bjork or Kate Bush.

But then again, they’re also chasing some pretty spectacular comets, particularly the geisha shapes of ‘Polar Magnets Parts 1 & 2’, the monolithic ‘Sea Change’ and the darkly charming ‘Last Bus’.

So, to sum up, The Sunburn Index is the confident second stage in a fluent evolution. And even the pyramids were built in incremental steps.