Here he was, a bright guy, experienced, ambitious, not little anymore, making short films on his own dime and immersing himself in the poems of Jacques Prévert at an expensive and prestigious university, and yet he was in peril of morphing into one of those dreaded Hollywood archetypes: the former child star. Danny Bonaduce with an Ivy League pedigree. Was there frustration? "Um, yeah," Joe says. "I would answer that question with a resounding yes. I was scared and depressed for a while. Not that I had any reason to fucking be depressed—I mean, I was going to college and everything. It was not like I was hungry. But absolutely. I was like, 'Shit, I don't know if anybody's gonna let me act. They'll let me be in another sitcom, but I don't want to do that. This is terrible.' Yeah."

And so that's when it began—or, more precisely, when it ended. That's when Joe clicked delete. "He's got a pinpointed focus about 'What do I really want, and how do I go about creating it?' " says his friend and fellow actor Carla Gugino. Joe came up with a plan. He stopped acting for a couple of years and finally emerged to launch what looks now, in retrospect, like a slow, smart, sustained campaign of reinvention. He gravitated toward Sundance films with the grit to scrape off layers of sitcom gloss. He started by playing a beaten-up gay hustler in 2004's Mysterious Skin, paying his own way to Kansas to visit the places where the characters lived. Then he played a Chandlerean teen gumshoe in Rian Johnson's Brick, an accident-haunted and brain-damaged bank janitor in Scott Frank's The Lookout, and a tormented Iraq War veteran in Kimberly Peirce's Stop-Loss. Last year he radiated dork charm as Tom, Zooey Deschanel's delusionally romantic officemate, in (500) Days of Summer, a role that landed him a Golden Globe nomination. Whenever the camera caught Joe in the crowd at the ceremony, he looked as though he'd geared up for the red carpet by chugging a quart of bliss juice.

By now you can watch Joe's movies back-to-back and not only will you fail to pick up remnants of that long-haired kid from 3rd Rock, you will see an actor whose identity seems to shift so fluidly from role to role that it's hard to pin down what an essential Joe-ness might be. (In an upcoming indie film called Hesher, he is nearly unrecognizable as a Dionysian death-metal sage with a shaggy mane, tattoos, and a fondness for blowing things up.) The essence of Joe is that he has no discernible essence. He occupies a state of perpetual flux. "Thank you!" Joe says when you point this out. "I take that as the highest compliment."

• • •

When Christopher Nolan and his stunt director approached Joe about the role in Inception, they told him it would hurt. "I wanted to paint a grim picture of it," Nolan says. "The worse I made it sound, the more Joe would grin." There would be pain. There would be wire work—jumping and fighting in a Fred Astaire-ishly spinning room. Joe would need to wear elbow pads, knee pads, torso pads. Avoiding injury would require relentless training. "They were basically saying, 'This will be really hard,' " Joe recalls. "And I said, 'I will do anything at all, and I will never complain once.' Chris just sort of smiled and said, 'Get it in writing.'"

Nolan wasn't lying. Joe went to England to shoot levitational hand-to-hand combat in a whirling tube set up in an old zeppelin factory, and "it was six-day weeks of just, like, coming home at night fuckin' battered. Like you are after you play a hard game of football," Joe says. "The light fixtures on the ceiling are coming around on the floor, and you have to choose the right time to cross through them, and if you don't, you're going to fall." Nevertheless, there is no record of Joe bitching on the set. "The adrenaline," he says, "was so nuts that I was like, 'This normally would have hurt a lot, but let's go again, let's go, let's go, let's go.'"