The people of Earth have become cicadas, sleeping for decades at a time, waking for a brief spell every 30 years, so as to be in "lockstep" with the lightspeed-lagged, spacefaring civilizations that have slowly (s-l-o-w-l-y) spread across the galaxy.
All the people of Earth that is, save The Million: a group of one million (plus or minus) people who live in realtime as aristocrats whose families each rule over vast estates populated by thousands of robots that see to their every need. The Million view themselves as the true inheritors of the Earth, the people who understand and tend it and truly own it, despite the thronging billions they must share it with a few times every generation when the cicadas come up out of their subterranean cold-sleep racks.
But that's not how the billions see it: as far as they're concerned, The Million are too-big-for-their-britches janitors who tend their cities while they undertake the thoroughly modern and civilized lifestyles of the slow sleeping, spacefaring post-humans.
Gavin Penn-of-Chaffee is a "visitor" — the generic term for an illegal alien in The Million's world. Some visitors are cicadas who've woken out of cycle; some are off-worlders; some are children birthed in secret in defiance of The Million's strictly managed fertility rules.
Gavin hides from the rest of The Million, his only companions his father and his brother Bernie, who suffered a brain injury as a young man and is now prone to fits of rage. Gavin's adventure starts when their father is killed and Bernie is framed for the murder, and Gavin must impersonate a legitimate member of The Million to try to clear Bernie's name, traveling to the museum city of Venice to train as an Auditor — the police force that mediates disputes among The Million and between them and the billions.
Schroeder's worldbuilding is, as always, dazzling — and, as always, ably matched by heart-pounding adventure plots that involve likeable, imperfect people who we can root for even as we fret that they are making foolish — but understandable — choices.
The answer to the riddle of Bernie's murder is a wonderful revelation, and the book sets up a sequel — most welcome, after the long gap between Lockstep and The Million.
The Million [Karl Schroeder/Tor]