Levin, a professor of physics and astronomy at Columbia whose last book documented the detection of gravitational waves, is a likeable guide to what we know and what we guess, and wherever the physics allows she is clear, straightforward and intuitive. The trouble is, black holes are none of those things, so this mind-bending little book is still, unavoidably, a difficult read at times. It’s a hugely enjoyable one, though. At the end of it you will know a lot about black holes, but you won’t understand them. At least you will have the comfort of knowing that nobody else does either … yet.