The second book of the Silo trilogy is just as much of a page-turner as the first one.

It starts in more-or-less current times and expands along several locations and timeslines on the background of the setting, detailing why the situation is the way it is, and just *how* fucked everything is.
It does this very well, it ups the stakes, it provides a ton of background lore, and really has me looking forward for the endgame in Dust.