He’s young (43). Comfortable on stage (played Sweeney Todd in high school). Has serious nerd credentials (Stanford, NeXT). Shares Steve Jobs’ obsession with detail (keeps a jeweler’s loupe in his office to check every pixel on every icon). And the division he heads — mobile software — drives nearly 70% of Apple’s (AAPL) income.

“He’s a sharp, down-to-earth, and talented engineer, and a more-than-decent presenter,” one entrepreneur told Adam Lashinsky. “He’s the total package.”

According to Lashinsky’s new book Inside Apple: How America’s Most Admired — and Secretive — Company Really Works, senior vice president Scott Forstall stands out among the rest of Apple’s executive team as the most likely to succeed Steve Jobs once the Tim Cook era is over.

If …

“If there’s a knock on Forstall,” writes Lashinsky, “it’s that he wears his ambition in plainer view than the typical Apple executive. He blatantly accumulated influence in recent years, including, it is whispered, when Jobs was on medical leave.”

Lashinsky’s profile of Forstall is likely to be closely read inside and outside the company. Scheduled to be released next week, Inside Apple is the most important Apple book since Walter Isaacson’s Steve Jobs. It is, in many ways, the perfect companion to the Jobs biography. If Isaacson’s was the Time Magazine or People Weekly version of the Apple story, what Lashinsky delivers — appropriately enough, given the magazine he works for — is the Fortune version.

Lashinsky’s goal was to understand the company Jobs built as a business. But unlike, Isaacson, Lashinsky didn’t have Jobs’ cooperation. Nor did the company make any Apple executives or employees available. So like a correspondent debriefing refugees at the border of a war zone, Lashinsky interviewed scores of collaborators, competitors and former employees after they left the confines of Apple’s closely guarded Cupertino campus.

The result is a deep dive into an extraordinary enterprise that has disrupted one industry after another while ignoring — if not deliberately breaking — most of the rules of modern business management.

Jobs, of course, looms large in Lashinsky’s narrative, as do CEO Tim Cook and design chief Jony Ive. But it’s Forstall who best fits Jobs’ mold and seems most likely to eventually succeed him.

“Whether Forstall will happily remain a supporting player,” Lashinsky writes, “will be one of the great internal dramas of Cook’s tenure.”