‘Shelter in place’ is a phrase the world is unexpectedly familiar with, something Bradley Garrett could not have predicted when he began his book on “the architecture of dread”. It turns out to be strangely timely.

Garrett is a social geographer and explorer, best known for the (often legally dubious) urban exploration that he photographs and documents on his website. He is also a geography professor and academic, and his new book combines the thrill of getting into unusual places with cultural commentary on their significance. What does it tell us about ourselves that there is a trend in bunker-building? Who’s doing it and what are their motives?

Bunker: Building for the End Times is written as a travelogue, as Garrett travels in search of bunkers and – just as importantly – the people building them, commissioning them and inhabiting them. He spends time with them, getting to know them in an admirably non-judgemental way reminiscent of Louis Theroux. We meet a man building a fortress for his family in Thailand, a community of survivalists buying into a former military site, or companies selling their bunker-building consultation services.

Some of these people are more likeable than others. There are those who are clearly out to protect themselves, and who are prepared to use their cache of weapons when the time comes. Others are more altruistic. There’s a fascinating chapter on Mormon prepping, which I didn’t know anything about – Mormons are equipped for doomsday so that they can run out and help others, and they have such well funded machinery behind it that they frequently assist in disaster relief in the US already.

There are also lots of scam artists, hyped projects that have clearly been oversold, and some very shady operators who are stoking up fears in order to profit from them. While some billionaires clearly have built themselves boltholes – Donald Trump isn’t the only one – it would be wise to read news stories about wealthy preppers with a pinch of salt. Besides, as he spends time with preppers of more modest means, Garrett muses that “the people who would fare best in a disaster would be those who had never bought into consumer culture in the first place.”

One of the interesting aspects of the book is investigating what it is that people fear. There are conspiracy theories, fear of pandemics or nuclear war, but much of what is driving the current boom is a vague dread, a general fear for the future. From an admittedly very low base, American companies selling domestic bunkers have apparently seen a 700% increase in orders since 2016. There has been a shift in the customer base: more people from the left of the political spectrum are seeking a safe place to escape to.

Climate change also features, and there’s a striking chapter on prepping in Australia, including ‘fire bunkers’ that will keep you alive underground for an hour if you are trapped on your property in an inferno. This is prepping for climate disaster, or for the chaos that might follow a climate related disaster.

Inequality is also a theme. Most bunkers are commissioned by the wealthy, in order to protect themselves and their families. When governments build them, it is almost always to protect politicians. The biggest and most elaborate hardened structures ever made were designed to ensure some kind of continuity of government in a nuclear disaster, while ordinary citizens are left to fend for themselves. Other countries have chosen differently. Sweden and Finland all maintain safe spaces for their entire citizenry and – top tip – Switzerland has more bunker places than it does residents.

I enjoyed this book, both in its commentary and its exploration. It is bold and curious, and I liked Garrett’s openness to people with strong and unusual opinions. Exploring bunkers is a strikingly useful way to interrogate the fears and preoccupations of the 21st century, and the book raises useful questions about adaptation, survival, and the conflicted nature of being prepared.

“In building these spaces,” writes Garrett, “there’s an implicit assumption that we have given up on fixing the world we broke.” On the other hand, one could also argue that all prepping “is born from hope: after all, only those who believe there will be a future prepare for one.”