"He's like a human CliffsNotes," says Beth Comstock, GE's CMO, who recently hired Grossman when she needed a quick study in the history of military strategy. Grossman isn't so much an expert on the topic as he is a professional autodidact. "I didn't fit in and wasn't good at very much," says Grossman of his childhood. "So I decided to become really good at learning." Now 38, he's transformed a side job—tutoring celebrities' kids while working in the film business—into a career as a cultural attaché for high-powered creative execs. Grossman meets with each of his dozen clients on a weekly or monthly basis to discuss a subject they want to learn more about. He then has his researchers at Grossman & Partners dive into the area and deliver a report. But he also schedules long conversations with his clients—and will even arrange dinners with experts on specific topics. "I don't work for people who want to fake it before a dinner party," says Grossman. "My job is to make you smarter."
Many of Grossman's clients like to keep their reliance on him under wraps. One media exec, who prefers not to be named, first heard of Grossman when he worked for Hollywood producer Brian Grazer. "I kept hearing that Brad was Brian's secret weapon," he says. The exec now meets with the New York–based Grossman once a week, typically at a restaurant or over Skype, to learn about everything from wine to how Darwinism might relate to managing tomorrow's workforce. "My job is to anticipate what comes next," the executive says. "It's hard to do that when you're stuck in meetings."
A version of this article appeared in the December 2013 / January 2014 issue of Fast Company magazine.