When twenty-eight-year-old San Francisco Daily Morning Call reporter Mark Twain met Tom Sawyer at a local bathhouse in 1863, he was seeking a subject for his first novel. As Twain steamed, played cards, and drank beer with Sawyer (a volunteer firefighter, customs inspector, and local hero responsible for having saved ninety lives at sea), he had second thoughts about Shirley Tempest, his proposed book about a local girl firefighter, and began to envision a novel of wider scope. Twain learned that a dozen years earlier the then-eighteen-year-old New York–born Sawyer had been a "Torch Boy," one of the youths who raced ahead of the volunteer firemen's hand-drawn engines at night carrying torches to light the way, always aware that a single spark could reduce the all-wood city of San Francisco to ashes in an instant. At that time a mysterious serial arsonist known by some as "The Lightkeeper" was in the process of burning San Francisco to the ground six times in eighteen months—the most disastrous and costly series of fires ever experienced by any American metropolis.

Black Fire is the most thorough and accurate account of Sawyer's relationship with Mark Twain and of the six devastating incendiary fires that baptized one of the modern world's favorite cities. Set amid a scorched landscape of burning roads, melting iron warehouses, exploding buildings, and deadly gangs who extorted and ruled by fear, it includes the never-before-told stories of Sawyer's heroism during the sinking of the steamship Independence and the crucial role Sawyer and the Torch Boys played in solving the mystery of the Lightkeeper.  

Drawing on archival sources such as actual San Francisco newspaper interviews with Sawyer and the handwritten police depositions of the arrest of the Lightkeeper, bestselling author Robert Graysmith vividly portrays the gritty, corrupt, and violent world of Gold Rush–era San Francisco, overrun with gunfighters, hooligans, hordes of gold prospectors, crooked politicians, and vigilantes. By chronicling how Sawyer took it upon himself to investigate, expose, and stop the arsonist, Black Fire details—for the first time—Sawyer's remarkable life and illustrates why Twain would later feel compelled to name his iconic character after his San Francisco buddy when he wrote The Adventures of Tom Sawyer.