Almost four years have passed since the release of the last Radiohead album, Hail to the Thief. That's a long spell without new material for the most important band in Britain, whose dense, cerebral 1997 masterpiece, OK Computer, frequently tops lists of the greatest of all time.

But even when they are quiet, the Oxford quintet are never really silent. This week, they dropped the biggest hint yet at the content of their seventh album, due in an unspecified month later this year.

At www.vapourbrothers.com, the website of the film-making team responsible for many of the band's videos, a surreal short film appeared, juxtaposing footage of the band in the studio with images of dancing skeletons, a matador being gored and a slowly rotating cow.

Alluding, no doubt ironically, to Radiohead's morbid mindset, we hear an announcer say, "Here is a land of happy, contented people". We see singer Thom Yorke dancing badly to old-school rave music, and playing guitar while bandmate Ed O'Brien lies on the floor shining a torch in his eyes. They wear Bush and Saddam masks as Yorke's characteristic stream-of-consciousness words flash up: "Capitalism. Millbank. Vermin. Cost". Make of that what you will.

The more this band communicate, the more they complicate the puzzle, but that is their appeal. They have become masters of the cryptic clue.

The chief source of information is www.radiohead.com/deadairspace, the band's blog, where photos appear of their grand studio room, of illustrator Stanley Donwood at work on the album sleeve, or simply of trees in the snow. More helpfully, a picture once popped up of a blackboard listing new song titles, including No Shame, Bodysnatchers and Arpeggi.

Yorke often chips in with enigmatic words and poor grammar, mostly about global warming, but occasionally he'll say something about the music, such as "some of the random stuff we have at the moment could be the most exciting ... trying to figure out how on earth we will be able to play some of it".

The Vapour Brothers' film seems to be hinting at a venture into even harsher electronica for the band. Then again, it also shows Yorke singing Winter Wonderland.

Numerous unreleased songs can already be found floating around on the web since the band's summer 2006 tour, and a few are already firm favourites. Especially worth digging out are Bangers and Mash and Go Slowly (at http://speedofdark-web.blogspot.com/2006/11/all-radioheadpart-three-of-three.html) and the gorgeous House of Cards (http://finefinemusic.com/2006/05/16/radiohead-houseofcards). Or you can watch filmed, high quality solo piano versions of Videotape and Down Is the New Up at www.fromthebasement.tv.

One final shot from the new video shows Yorke holding up a sign reading: "One day all this will become clear". With autumn looking like the likely time for LP7 to be unveiled, the mystery will soon be over. Until then, let's enjoy the confusion.