Since 2017, the UK has seen fifteen terrible terrorist attacks. But the atrocities on our evening news are the tip of a vast iceberg. Security services are striving to contain a staggering 3,000 jihadists, far-right extremists and other potential threats. We are in a new age of terror, with self-radicalising, hard-to-categorise individuals planning violence—but each one caught by the British state tells us something about British society.

For every successful plot in the five years since Westminster Bridge, more than twice as many have been foiled. Some were thwarted by nerve-wracking undercover operations; others were narrowly averted by heroic citizens, or ruined by the absurd mistakes of would-be attackers. Invariably, the all-too-human stories of these failed terrorists reveal the true picture of UK extremism.

Through interviews with senior counter-terror figures and astonishing court testimony, Plotters unpacks how and why British terror attacks happen—and don’t. From dating websites and prison cells to Telegram networks and Tesco knives, Lizzie Dearden’s deep dive offers one disturbing certainty: the plotters will keep coming. To confront them, we need to understand them.