When Martha Plimpton speaks, it’s with a sharp wit, self-awareness, and the kind of honesty that has made her one of Hollywood’s most enduring—and endearing—personalities.

Now at 54, the actress and activist has made headlines not for a new role, but for a fresh start across the Atlantic. In a recent candid interview, she opened up about her move to London, a complicated mother-daughter dynamic, and an intriguing new collaboration with none other than Mark Ruffalo.

Plimpton’s decision to relocate to London wasn’t entirely impulsive, but it also wasn’t part of some master plan. “I came over for work originally,” she explains. “And then, one day, I just realized—I didn’t want to leave.”

The city’s pace, the culture, and its theater scene gave her the creative recharge she didn’t know she needed. “London’s got this beautiful, messy, honest energy,” she says. “It reminded me of why I fell in love with acting in the first place.”

Since the move, she’s become something of a regular on the London stage, most recently earning acclaim for her role in a revival of A Doll’s House. “There’s something about British audiences—they’re patient,” Plimpton notes. “They listen.

You can feel it from the stage. And for an actor, that’s gold.” She admits that adapting to a different lifestyle hasn’t been seamless. “I still don’t understand how the heating works in these old houses,” she jokes. “And I miss New York pizza like a limb.”

Still, the decision to uproot wasn’t met with enthusiasm from everyone in her life—least of all her mother, actress Shelley Plimpton. Martha laughs when asked about their relationship, but it’s clear there’s both affection and complexity there.

“My mother recently called me a hoarder,” she reveals with a chuckle. “And she wasn’t joking.” According to Plimpton, her mother visited her London flat and was horrified by the “organized chaos” of her belongings. “I have this habit of collecting things—books, playbills, vintage clothes—and to her, that’s the same as hoarding.”

She insists, of course, that she’s not a hoarder in the clinical sense. “I just have a lot of things that mean something to me,” she says, more seriously. “But I get it. She’s very minimalist. I’m maximalist. It’s generational, maybe.”

Their relationship, she admits, is a mix of sharp critiques and unconditional love. “We’ve always been a little oil and water, but she’s one of the funniest people I know. And she’ll always tell me the truth—even if I don’t want to hear it.”

While Plimpton continues to balance personal quirks with professional ambition, her latest project might be the most surprising yet. She’s working with Mark Ruffalo on an ambitious independent film, currently in pre-production.

The project—tentatively titled Task—is described as a dark comedy about two estranged siblings forced to work together after inheriting their father’s bizarre business: a private company that helps people “emotionally outsource” difficult conversations.

“It’s one of the strangest, funniest scripts I’ve ever read,” Plimpton says with enthusiasm. “And Mark is just a dream. He’s intense, but so generous. We’re playing these siblings who absolutely can’t stand each other—but have this weird, undeniable bond.”

The film is being helmed by an up-and-coming British director, and the plan is to shoot in both London and the northeastern U.S., where the characters’ story begins.

Plimpton and Ruffalo, she says, share a natural chemistry, even though they’d never worked together before. “There’s something kind of feral about Mark,” she laughs. “He’s always working just below the surface, and you can’t predict what he’s going to do next.

That makes it incredibly fun—and a little terrifying.” The duo has already begun table reads and creative sessions via Zoom, and production is expected to begin early next year.

For Plimpton, the project is more than just a creative endeavor—it’s a return to the kind of grounded, character-driven storytelling she’s always loved. “After a while, you realize the things you want to do don’t have to be big,” she reflects. “They just have to be real.” She’s drawn to characters who are flawed, complicated, and, in her words, “maybe a little messy—like all of us.”

Despite the high-profile collaborations and overseas success, Plimpton is remarkably grounded about her place in the industry. “I’ve never been the type to chase celebrity,” she says. “I like doing good work. I like surprising people. I like doing stuff that makes me laugh or cry or think. And if I can pay my rent doing that, I’m lucky.”

She’s also vocal about the importance of using her platform for advocacy. A longtime supporter of reproductive rights, Plimpton continues to speak out on political and social issues, even as she balances a demanding career. “I think if you have a voice, you should use it,” she says plainly. “Even if it ruffles feathers. Especially if it does.”

Asked whether London has changed her, she pauses. “Yes and no,” she says. “I think being here has allowed me to slow down, look at things a little differently. But I’m still me. I’m still a loudmouth with a pile of books next to my bed and a thousand pairs of vintage boots I refuse to throw away.”

She’s not sure how long she’ll stay in London—“maybe a few years, maybe forever”—but for now, it feels like home. “There’s something about being in a new place that keeps you curious,” she says. “And curiosity, I think, is the thing that keeps you alive.”

Her schedule is packed—rehearsals, filming prep, a few voiceover gigs—but she insists she’s trying to enjoy the quiet moments, too. Long walks in Hyde Park, trips to obscure bookshops, and dinners with theater friends who somehow make time between shows. “It’s a good life,” she says. “A weird one, but a good one.”

As for what’s next, she’s taking it one day at a time. “I don’t have a five-year plan,” Plimpton shrugs. “I’ve never had one. I just try to do good work, stay weird, and not let my mother throw out my stuff when she visits.”