An aluminium can travelling along a conveyor is thrown sideways into its own bin without anything touching it. A drum spinning beneath the belt sweeps a magnetic field across the metal, the field induces a current in it, and the current makes a field of its own that pushes back. Non-magnetic metal, moved by magnetism.

Nora Whitfield takes a household bin apart machine by machine, and each one turns out to work the same way: find a physical property the materials do not share, then exploit it. Size, for a rotating screen. Density, for an air classifier. Reflectance in the near infrared, for the sensors that identify polymers by the light they return — and which quietly let black plastic through, because a black object returns almost nothing to read.

What emerges is a bale, and a bale is a commodity. It is sold against a written specification to a buyer who may refuse it. That is the pivot of the book: whether an object is recycled is decided not at the kerb but at a mill, on price. When China restricted imports in 2018 and a long-standing destination for the world's lower-grade plastic disappeared, nothing about the material changed; only the buyer did, and programmes closed on both sides of the Pacific.

The book then follows what does not get sold. A landfill is described as what it actually is — an engineered containment structure with a barrier at the bottom, pipes to draw off the liquid that rain creates as it passes through, and a monitoring obligation that outlasts the working life of the site. The gas that decomposition produces is drawn out through wells under vacuum, and the capture percentages so often quoted turn out to depend on how and when anyone measured.

Incineration closes the sequence. It shrinks what it burns without removing it from the world: the flue gas is cleaned, and the cleaning concentrates what it captures into ash, some destined for construction aggregate and some for treatment as hazardous material.

The final chapter is about arithmetic — what a recycling rate counts, what it omits, and how far a headline figure can move while nothing at all changes on the ground.