Graphics that reference both the band's OK Computer-era artwork and the lyrics to "Fitter Happier" have been spotted in a handful of cities around the world, including London, Berlin, Los Angeles, New York and Amsterdam.
UPDATE (4/25, 3:30 p.m. EDT): As readers have now pointed out, the mysterious posters have also been spotted at various locations in Vancouver. So our bets are on these also being around other Canadian cities as well if you go hunting.
You can find some photos of the posters below.
Reddit sleuths are already working to crack the case, while the band's visual collaborator Stanley Donwood also teased a new Radiohead-related project on Instagram earlier this month. His account currently features pictures of scaffolding.
OK Computer was originally released in June 1997 (or May 1997 in Japan, if you want to get technical about it), so it shouldn't be long before this mystery reveals itself.
In other recent Radiohead news, the band were called upon to cancel a forthcoming concert in Israel in an open letter signed by Roger Waters, Thurston Moore, Tunde Adebimpe and more, while they also had a new species of ant named in their honour.
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