On December 14, 2012, 26 people at Sandy Hook Elementary School in Newtown, Conn., including 20 children barely older than toddlers, were shot and killed. It felt like a line in the sand, on gun violence and safety. Instead, nine years on, Sandy Hook has become a foundational story, and a symbol: of how malevolent, profit-motivated actors use the internet to terrorize the vulnerable, even the families of murdered children, and how conspiracy has gained traction in our world.

In the wake of the tragedy, parents of the young victims have been accosted on the street. They are harassed online. They are stalked and forced out of the towns they live in. Someone shot a rifle into the home of one parent.

But the conspiracy has asked the victims and survivors themselves to defend that the event even occurred. At the center of conspiracy theorists’ crusade is Alex Jones’s InfoWars, where hoaxers air noxious theories and raise money. Egged on by Jones, emboldened by online anonymity, his followers’ questions grew into suspicion, suspicion into demands for proof, unanswered demands into rage, with a through line straight to January 6.

Through exhaustive reporting, narrative storytelling, and intimate portraits, Sandy Hook is the definitive book on one of the most shocking cultural ruptures of the internet age.