I don’t recall where I first heard about this . It was probably Warren Ellis, but I seem to recall there being a second source. Anyway, I lived in Turin, or between Turin and my then-home in Walthamstow, for the best part of a year, 1989–90. My employers had a big contract with an Italian bank, and most of the work was done on site. Which seems amazingly old-fashioned for software development today, when we mostly don’t even visit our employers' premises very often.

All of which has nothing to do with the novel. It was written in the 70s and is set then. The unnamed first-person narrator is researching the titular event, which happened ten years earlier. It’s not entirely clear to what extent he experienced the ‘Twenty Days’ himself, but many people still living in the city did, and they don’t talk about it. It started with mass insomnia. Sleepless people took to the streets, some in their nightclothes. Then the violence started. Mysterious, brutal murders of the insomniacs.

But before all that, there was the Library. It seemed to be a project by well-meaning young people, possibly religious, who set up a kind of pre-computer social network. People were encouraged to share diaries or other writing — original manuscripts only, no published work. For a small fee, anyone could visit the archive thus formed, and read any of the pieces. For slightly higher fee, they could find the name and address of a chosen contributor.

The idea being ostensibly to help lonely people find like-minded folks. With a strange inevitability, that isn’t necessarily how it was used.

The implication is the Library somehow led to the sleeplessness, if not the violence. Perhaps not the violence, as our narrator’s explorations appear to find a more supernatural, if not downright bizarre, explanation for that.

And it all seems to be starting up again. The Library didn’t go away, it just went underground. And the narrator and at least one of his interviewees may be in danger.

It’s an odd one this. Reviews of the recent English-language publication speak of its prescience, comparing the combination of the Library and the insomnia with people up all night doomscrolling on their phones. Which is interesting, but takes no account of the violent attacks, and the supernatural element.

I think this will bear repeated readings.