This month sees the 20th anniversary of R.E.M.'s Monster. Perennially seen as the misfit in the band's back catalogue, it represented an electrifying return to the rock of their I.R.S. years after the unprecedented success of 1992's Automatic for the People.

But before we get to the music, consider what kind of visual statement Monster makes, because it is substantial. That Sainsbury's-bag orange. That hulking, blurry, non-specific mammal on the front cover. The band's name blazing away, siren-blue in the corner. Without even listening to it, you'd know this was a different beast from R.E.M's two preceding albums Out of Time and Automatic for the People; and so it proved to be.

This is the album where Stipe and co. left the mandolins in the studio car park and plugged in their guitars again, creating an irresistible suite of bold, seductive noise poems. Those only familiar with 'Everybody Hurts' and 'Shiny Happy People' were in for a bit of a shock; from the rasping opening chords of 'What's The Frequency, Kenneth?' to Stipe's final howl on 'You', the band come on with big riffs, pulsating effects and, well, a bit of an attitude.

Of course, for those who had been with R.E.M. from the start, Monster seemed more a record of release than reinvention. Out of Time and Automatic for the People were remarkable successes both artistically and commercially, but the band had never been ones to settle. Eager to tour again, the band drew from their past while also working on an arena-friendly vehicle for Stipe's often cryptic lyrics. So there are some tracks on Monster whose closest relations can be found on Document (their final studio album on I.R.S) or even as far back as Reckoning. But for all that Monster harked back to their college rock years, there were still elements that were entirely new: the new-found leaning towards effects pedals, for example (particularly on the glorious 'What's The Frequency...' and 'Bang And Blame'), and a previously untapped lyrical preoccupation with fame, sexuality and paranoia.

The latter was perhaps understandable; when Monster was released, the band was one of the most popular in the world, despite not having toured for nearly four years. Rumours about Stipe's sexuality also began to circulate at this stage, though he didn't officially come out until 2001. (The subsequent Monster tour was fraught - Stipe required a hernia operation halfway through, and drummer Bill Berry suffered a brain aneurysm onstage that would eventually lead to his leaving the band.)

Monster also contains some of R.E.M.'s most experimental material - the churning 'King of Comedy' (which took its name from the Scorcese film of the same name) is kinetic and funky, and is the undoubted highlight of the surround-sound version of the album released a couple of years back. Then there's 'Tongue', an organ-led soul number featuring an exquisite, pained falsetto from Stipe - which also appears on 'I Don't Sleep, I Dream', with the deliciously suggestive "I'll settle for a cup of coffee, but you know what I really need." The success of these two tracks leads me to wonder why Stipe didn't use this aspect of his vocal range more often; they are stunning.

Other highlights include the graceful 'Strange Currencies'; the clipped riffs of 'Star 69' and glam-rock shapes of 'Crush With Eyeliner'. The real jewel in Monster's crown, though, is 'Let Me In' - Stipe's lament for his friend Kurt, who killed himself that year. Over a single, heavily processed guitar, Stipe's voice glides, growls and weaves around the darkest lyrics he has ever written. It achieves devastation and elation simultaneously; much like Nirvana strove to. Not only is it the best song on Monster, it is one of R.E.M.'s best, period.

Some say Monster is best taken on its own terms, to be treated almost as a curio in their storied back catalogue - and while it is certainly an unusual offering, it is also the most purely enjoyable, cohesive and downright thrilling album the band put out. If you've yet to hear it, seek it out; you won't be disappointed. And you certainly won't have trouble picking it out on the shelves.

Monster was originally released on September 26th, 1994 by Warner Bros. Records.