Birnam Wood is a guerrilla gardening collective in New Zealand — a few dozen people who plant crops on land nobody’s watching, roadsides, dead lots, farms gone fallow, sometimes with permission and sometimes not. Mira runs it, and after five years it’s still broke. Then a landslide cuts off a town on the South Island and strands a big farm, and she figures that’s five thousand acres nobody’s looking at. Except someone is. An American billionaire, Robert Lemoine, who made his money in surveillance drones, has bought the place and told everyone he’s building a doomsday bunker. He catches Mira on the property and, instead of running her off, offers to bankroll the whole operation. What he’s actually doing up there is the engine of the book, and Catton lets everybody talk themselves into the deal for reasons that make sense at the time. It’s a thriller that also skewers everyone in it, and it turns brutal at the end. Loved it? Loved it.