Writer Philip Roth is the subject of PBS's "American Masters Philip Roth: Unmasked," premiering on Friday, March 29.

Speakeasy has an exclusive preview of the film in which Roth, who just turned 80 years old yesterday, delves into his writing process. "I invent a character as I go along," he says. "You must find everything about this man. Who he is, where he's from, what he's done, what his family is. Then I get to his wife."

Roth says, "There's a journalistic side to writing novels," in the collecting of information and details. "You can't invent off of nothing." As an example, he describes his research of taxidermy in order to write "I Married a Communist," the time he went to "this stinking taxidermy place" in New Jersey.

Watch the clip.