Since he publicly addressed the personal and label-related issues that were blocking his creative process around the time of 2005’s With Teeth album, the last couple of years have seen Trent Reznor and his Nine Inch Nails project hit a previously unseen level of prolificity, releasing last year’s Year Zero collection and its companion remix set, handling partial production for Saul Williams’ Niggy Tardust download album, and now this sprawling 2-disc instrumental set (alongside yet another new NIN album – the free-to-download The Slip).

Designed to work as a series of ‘imaginary soundtracks.’ (check out the accompanying film festival on Youtube), Ghosts I-IV sees Reznor assembling a cast of studio collaborators including With Teeth/Year Zero co-producer Atticus Ross, King Crimson guitarist Adrian Belew and Dresden Dolls drummer Brian Viglione to craft 36 comparatively short instrumental ‘vignettes’ across the two discs here. In many senses the resulting atmosphere conjured comes across as similar to the quieter instrumental segue tracks previously tucked in amongst the tracklisting of NIN albums such as Help Me I Am In Hell, A Warm Place or The Frail, the chief difference here being that the sense atmosphere is sustained for an epic 110 minutes, resulting perhaps in the impression of four parallel Ghosts suites more than anything else. Indeed, many of Ghosts’ most striking and beguiling moments arrive when Reznor takes a stylistic departure from the processed, aggressive rock he’s built an arena-filling reputation upon.

If Disc 1’s opening track could almost pass for a previously unreleased segue track from The Fragile with its delicate, melancholic piano keys trailing out over a gradually building backdrop of vocal drone textures, Track 2 sees Reznor venturing considerably further out towards avante-classical/ambient than he’s ever gone previously, as glacial Eno-esque chords float amidst a planktonic broth of brooding synthetic drones and buzzing noise, resulting in a moment that’s equally as vulnerable as it is ominous. Track 5 meanwhile calls to mind some lost score to a David Lynch movie, as twanging vintage guitar strokes echo out over distant, muffled rhythmic loops and a descending piano motif that’s one part lounge-jazz, the other Closer outro in one of the most immediately cinematic-sounding offerings on the first disc, before Track 11 sees the inspired incorporation of orchestral elements as menacing cello strokes and chaotic sampled string flourishes twirl and slide around a backbone of sparse, skeletal-sounding percussion.

Elsewhere on Disc 2 however, Track 8 represents the opposite end of the equation, with its tight, aggressive fusion of martial rock drums, funky slap bass riffs and drilling walls of distorted guitars. It’s pretty much a standard NIN rock moment sans the vocals, while Track 6’s wander out into electro-EBM, complete with sampled horror-movie screams, while certainly offering up one of few danceable tracks here, comes across as being the sort of thing Skinny Puppy would have considered too hammy somewhere around 1996.

That said however, while there’s the occasional sense that Reznor could’ve perhaps trimmed this collection down slightly, it’s certainly hardly ‘Brian Eno with training wheels’ as another particularly uncharitable critic put it. When Ghosts manages to throw off the industrial-rock past that’s increasingly become something of a straitjacket for Reznor in recent years, it really manages to fly, offering far more truly inspired moments than many similar ‘classical/ambient’ from more academically-feted names manage.

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