Timothy McVeigh, the right-wing terrorist who killed 168 people in the 1995 Oklahoma City bombing, cared about one issue above all others: guns. To him, guns were synonymous with freedom, and any government attempt to regulate them meant incipient tyranny.

“When it came to guns,” writes Jeffrey Toobin in “Homegrown,” his compelling new book about the Oklahoma City attack, “McVeigh did more than simply advocate for his own right to own and use firearms; he joined an ascendant political crusade, which grew more extreme over the course of his lifetime and beyond.”