“It’s not easy with divorce,” she adds.

Although she dreamed from an early age of being an actress, she was initially reluctant to articulate that. She didn’t want to get ahead of herself, didn’t want to denigrate the profession by implying that it required anything less than years of preparation. At Brown she majored in theater arts, then continued her studies at Juilliard.

“Her sole ambition was to be a member of a repertory company somewhere in the United States and to do roles in plays, one after the other,” according to the theater director Daisy Prince, the daughter of Harold Prince and a close friend of Linney’s since their time together at Brown. Hickey, her brother on “The Big C,” knew her at Juilliard, and remembers her as a tomboy, “not immediately glamorous,” whose only discernible vanity was her alabaster skin, which she carefully protected from the sun. It was so sensitive, he says, that whenever he kissed her on the cheek, “she’d literally almost be in hives.”

LINNEY SAYS SHE ENDED up doing screen work because a veteran stage actor she respected told her she should “always say yes to experience.” So when she was offered a small part in the 1992 movie “Lorenzo’s Oil,” she took it. A bigger role and bigger break came the next year, with “Tales of the City,” in which she played the central role of Mary Ann Singleton, a blushing Dorothy in the sybaritic Oz of 1970s San Francisco. The first images of her in that miniseries remain indelible: brand new in town and dressed in a red, white and blue outfit seemingly borrowed from a flight attendant, she wheels a periwinkle suitcase with flower decals on it across the street. When she goes to the supermarket and realizes that the cute guy chatting her up in the produce aisle belongs to an even cuter guy a few feet away, she’s dumbfounded.

Linney could have easily been typecast from then on as a naïf. She didn’t have the distinctive beauty of many a leading lady; she didn’t have the edge or flagrant sexiness to pull off a femme fatale. A surface reading of her said “vanilla” — or maybe, given the air of Southern graciousness passed down from her mother, “butter pecan” — but nothing more complicated than that.

And to some extent, at least on screen, she was indeed confined to a limited spectrum for a while. The archetypal Linney character had a Pollyanna patina, which made her welling glimmers of unease and her eventual outbursts all the more jolting. Linney played that kind of part in “The Truman Show,” opposite Jim Carrey; in “Primal Fear,” opposite Richard Gere; and in “You Can Count on Me,” opposite Mark Ruffalo, the 2000 movie that elevated her to a whole new level of regard. Several critics circles gave her their best-actress awards for “You Can Count on Me,” and she received her first Oscar nomination for it.

But it was an extremely difficult period of her life. The shooting of the movie, for which the director Kenneth Lonergan had only a minuscule budget, was a real slog, Ruffalo recalls. “We shared an old chicken coop that was our dressing room,” he says, referring to the shoot’s location in upstate New York. “We were staying in a musty, moldy hotel: a sort of summer bungalow kind of thing. It was hot, the crew was underpaid, people were underfed, there was always some problem with money going on.” And he says that Linney and Lonergan didn’t always agree on how she should play her part as the responsible and aggrieved sister of a beloved brother (Ruffalo) who just won’t grow up. “I could see her getting frustrated about it,” he says.

Around the time that Linney was working through this, a house she owned in rural Connecticut burned down, set ablaze when a clump of rags soaked in linseed oil caught fire. And “You Can Count on Me” was released as her first marriage, to the actor David Adkins, unraveled after five years. The acclaim the movie wound up bringing her was somewhat eclipsed by these and other hardships, including a stalker who for several years sent her photos, letters and gifts, always knowing where to find her. “He infiltrated every area of my life,” she says. “Everywhere I would show up, there would be flowers. I mean everywhere I showed up. I went to Alaska — I was teaching — and he found out, and there were flowers.”