“To me, graffiti writers were the eccentrics and mad geniuses of hip-hop. They labored in obscurity. There were so many paradoxes in their art and how they thought about it. It was art and vandalism. ... Even the words to describe it: They’d use ‘beautify’ and ‘destroy’ interchangeably, with all this language of violence and destruction — bombing trains, killing lines. There was always something epic about graffiti.”

Rage is Back is a bracingly funny book, largely due to Dondi’s magnetic narration (“I was gonna do this as a footnote,” he explains, in describing one scene, “but I think it’s disrespectful to make a motherf----- rove his eyes all the way down to the bottom of the page and up again — plus, if the words matter, print them in a font I can read, you know?”).

Mansbach said he’s never had so much fun writing anything. A white writer telling a story from the point of view of a black teenager is often eyeballed uneasily by critics, but Mansbach gets Dondi just right, and nobody is complaining yet.

“It’s something I don’t do lightly,” says Mansbach, who is also the author of Angry Black White Boy, a satire about a white kid deeply invested in hip-hop. “I’ve been engaged with these issues in a pretty serious way, and the stakes are higher. But that’s true any time you’re writing a character of another race or genre, a male writer writing a female character or a straight writer writing a gay character.”

For all his fine comic writing, Mansbach doesn’t neglect the more serious aspects of New York City’s battle over graffiti in Rage is Back.

“The war on graffiti in many ways was a war on young people, young people of color in particular,” he says. “The reaction to graffiti opened the door and ushered in a lot of what we see today in public policy: the zero tolerance policy, misdemeanors being elevated to felony. Graffiti is also a window into sociology. ... It’s poignant: The guys who invented graffiti watched it die in front of them. By the ’90s the city had won. They buffed trains clean before they left the yard.”

If Rage is Back is any indication, Mansbach is nostalgic for the old days.

“The evolution of the art on the train happened so rapidly, it’s a compressed history of art, like going from cave drawings to Cubism in five years,” he marvels. “There was an intensity to it. A lot of the old-school writers said things evolved so fast you couldn’t leave the city. ... They’d say, ‘I can’t go on vacation, I gotta sit on the benches and see what rolls by.’

“There was nothing remunerative to it. These kids were devoted to it with a purity and a drive that is hard to imagine today. The world is so different. Now they’d be Instagramming it.”

Exploring such complexity, of course, is one of the things Mansbach likes best about being a writer.

“Complexity always draws me — like loving your kid to death but being willing to do anything to get out of the room.”