Operating out of a tiny office on Madison Avenue in the early 1960s, a struggling company called Marvel Comics presented a cast of brightly costumed characters distinguished by smart banter and compellingly human flaws. Spider-Man, the Fantastic Four, Captain America, the Incredible Hulk, the Avengers, Iron Man, Thor, the X-Men, Daredevil—these superheroes quickly won children's hearts and sparked the imaginations of pop artists, public intellectuals, and campus radicals. Over the course of a half century, Marvel's epic universe would become the most elaborate fictional narrative in history and serve as a modern American mythology for millions of readers.

Throughout this decades-long journey to becoming a multibillion-dollar enterprise, Marvel's identity has continually shifted, careening between scrappy underdog and corporate behemoth. As the company has weathered Wall Street machinations, Hollywood failures, and the collapse of the comic book market, its characters have been passed along among generations of editors, artists, and writers—also known as the celebrated Marvel "Bullpen." Entrusted to carry on tradition, Marvel's contributors—impoverished child prodigies, hallucinating peaceniks, and mercenary careerists among them—struggled with commercial mandates, a fickle audience, and, over matters of credit and control, one another.

For the first time, Marvel Comics reveals the outsized personalities behind the scenes, including Martin Goodman, the self-made publisher who forayed into comics after a get-rich-quick tip in 1939; Stan Lee, the energetic editor who would shepherd the company through thick and thin for decades; and Jack Kirby, the World War II veteran who'd co-created Captain America in 1940 and, twenty years later, developed with Lee the bulk of the company's marquee characters in a three-year frenzy of creativity that would be the grounds for future legal battles and endless debates.