How do you mend a broken Heart? Ann and Nancy Wilson know.

Then came that night in 2016. Ann, the singer and older sister, and Nancy, the guitarist, were rocking a Seattle-area amphitheater with their rendition of “Stairway to Heaven” when everything went down on the tour bus. Ann’s new husband, Dean Wetter, blew up at Nancy’s teenage sons about something, and it got physical. He was arrested. Rolling Stone did a mortifying story about the whole mess.

The tour sputtered on, but after that there would be separate dressing rooms, separate makeup artists, separate managers, separate camps.

The distance even became formalized by contract into what they called “sanctuary zones.” When they were offstage, Ann’s husband and manager were not to step into Nancy’s space. Nancy’s husband and manager were barred from venturing into Ann’s.

And yet last month, there were Nancy and Ann, sitting comfortably in Ann’s dressing room at Tampa’s Amalie Arena, talking about music until it was time for the buses to roll out. They had just delivered a stunning performance — and, as usual, they would be the toughest critics of it.

Nancy, 70, copped to “spacing out” and flubbing their new a cappella outro for “Never.” Ann, 73, took responsibility for a few fleeting coughs during the set, explaining that she was getting over a respiratory illness. (“If I drop a word or two because my lungs close up on me, so be it.”) But they agreed it was their best since the tour kicked off a week earlier: Their harmonies on “Dog & Butterfly.” The way they slid from “Straight On” into the groovy cover of David Bowie’s “Let’s Dance.” Their smoking-hot band of crack studio players recruited from Nashville.

“There’s no sanctuary in here,” said Ann’s personal assistant, Criss Cain, happily.

“We got tired of it,” said hair and makeup artist Sydniiee Oliveira.

On paper, the sanctuary zones were still in effect. The Wilson sisters had simply decided to ignore them.

“Unnecessary,” said Ann.

“It was unnecessary,” echoed Nancy. “To have a camp over here, a camp over there.”

The Wilsons were inseparable.

“So close,” recalled Kelly Curtis, a childhood friend who would work for Heart in the 1970s before becoming Pearl Jam’s longtime manager. “They went through everything. Boyfriends together, and music together. And it was unbreakable.”

At school, Ann stuck out in her edgy, Swingin’ London-inspired fashion choices.

“Boys. Social status. I didn’t care about any of those things at that time in high school,” she said.

After graduation, Ann followed her own path, singing in local rock bands. In 1971, she answered a newspaper ad placed by guitarist Roger Fisher and bassist Steve Fossen. They had led a series of groups with different names — including Heart — and they were looking for a lead singer. Through them, she met Roger’s older brother Michael and fell in love. She and her bandmates followed Michael to Vancouver, B.C., and they lived together in the kind of commune where it wasn’t unusual to see hippies playing naked badminton in the yard.

Producer Mike Flicker heard Heart on a scouting mission for Mushroom Records.

“The range and power of Ann’s voice blew me away,” he said.

Flicker wanted to sign just her, but Michael Fisher — at this point Heart’s manager — refused to make the deal without Roger. Flicker walked away. About six months later, Nancy dropped out of college, where she had been studying creative writing and literature, and moved north to join her sister in Heart. Suddenly, Flicker was interested in a package deal. He wanted those blood harmonies. He wanted Ann and Nancy.

“Heart without Nancy was a good cover band with a dynamite singer,” Flicker said. “With Nancy, it was like one plus one equaled 10.” In the end, he signed the whole band.

In the era of Boygenius, St. Vincent and Sleater-Kinney, it may be hard to imagine Heart as revolutionary — but that’s exactly what the Wilson sisters were.

“It was something we’d never seen, this amazing duo of women rocking out,” said Ben Mink, who would go on to produce K.D. Lang and Barenaked Ladies but first saw Heart in the mid-’70s playing a run at Lucifer’s nightclub in Calgary.

Bluegrass superstar Alison Krauss, a teenager when she encountered Heart a decade later, was mesmerized.

“They were the most mysterious people,” said Krauss. “You didn’t get to know anything, and the music spoke for itself. Maybe they’re tired of hearing this, but they’re such beautiful women. And that combination with what they were doing … you almost didn’t know where to place it.”

For Pearl Jam guitarist Mike McCready, who was growing up in Seattle in the 1980s, Heart became his role model.

“They were an example of someone that had done good in the Northwest, and there weren’t a lot of other examples,” he said. “So those songs at that time, ‘Barracuda’ and ‘Crazy on You,’ were integral to me going, ‘Oh, yeah, maybe I can do this.’”

Heart’s first big hit, “Magic Man,” in 1975, was penned by the sisters and inspired by Ann’s complex relationship with Michael. And then Nancy hooked up with Roger Fisher.

Publicly, the Wilson sisters and Fisher brothers made light of the intertwining, calling themselves the Wilshers. Privately, the entanglements were difficult. Michael Fisher was not just managing Heart. He was managing the intimate details of Ann’s life, telling her what to eat and what to wear.

“That’s what I was there for,” he said, without apology. “I was there to make that group successful. So, what she wore and what she ate were really important.”

Said Ann, half a century later: “I will never reconcile with the idea that I allowed myself to be controlled like that.”

The end for the Fisher brothers came in the late 1970s when both were caught with other women and were rapidly ejected from the band’s orbit, though today they insist they’ve been unfairly villainized. The cycle of dysfunction carried on when Nancy rebounded with the band’s drummer, Michael Derosier. By 1982, the original Heart was done.

“Fleetwood Mac, we lived that,” said Brian Foraker, the band’s longtime engineer. “There was magic with the original band. But you don’t sleep with the lead singer.”

Not surprisingly, memories of Heart 1.0 do not make the sisters feel warm and fuzzy.

As the new tour got underway last month, Ann’s manager, Dave Frey, was talking up a “big offer” on the table to reunite the old bandmates. The Gorge Amphitheatre in Washington state wanted the classic 1975 lineup for a concert commemorating the 50th anniversary of Heart’s debut album, “Dreamboat Annie.” Frey knew, from past discussions, that Roger Fisher, Fossen, Derosier and guitarist Howard Leese would be interested.

“And Ann was like, ‘If we’re going in the way-back machine, let’s do it,’” Frey said. “Six-way split. Everybody has to say yes or it doesn’t happen. Let’s shoot a documentary. Let’s make it cool. And there’s some edge to it.”

He paused.

“But I don’t think Nancy’s going to join,” he said. “So the next question is, we can’t call it Heart because Nancy owns half the company. So it would have to be, you know, ‘50 years of “Dreamboat Annie” featuring Ann Wilson, Steve Fossen, Roger Fisher, Derosier, etc.’”

Asked about a Wilsher reunion, Ann sounded less than thrilled.

“The thing that the fans don’t ever consider is the unpleasantness of how the relationships within the band function,” she said during a Nashville recording session. “If the band split up, there was a reason for that.”

Nancy, catching wind of the Gorge offer for the first time in a conversation with this reporter, was more blunt.

“I don’t think you could pay me enough,” she said. “It’s … what’s the word? It’s icky.”

With the close of the Wilsher era, Heart stumbled into the 1980s. Its next couple of albums failed to gain much traction in a musical landscape transformed by MTV and a new British Invasion that favored synth-poppy melodies over chugging guitars.

Soon, Fossen and Derosier exited, as well, and Heart became ever more synonymous with the Wilson sisters. Yet men continued to complicate their once-intertwined lives, personally and professionally.

The Wilsons acceded to the industry’s demand that they change up their look, going big-haired and glam in cheesy corset-wear for their 1985 self-titled album — which, as it happened, turned out to be their biggest ever. The quintuple-platinum release spawned four top 10 singles: “What About Love,” “These Dreams,” “Never” and “Nothin’ at All.”

Nancy wed Cameron Crowe, the rock journalist turned film director, and would go on to work with him on the music for such movies as “Say Anything,” “Jerry Maguire” and his slightly fictionalized autobiopic, “Almost Famous.” But they would also struggle for years to have children, until the birth of their twin sons in 2000. They divorced in 2010.

But in the early 1980s, she encountered yet another music-industry guy who would go on to play an enduring and disruptive role in her relationship with her sister and the music career they had built together.

That was Dean Wetter, a former manager of Derosier’s band. Impressed by his erudition and conversational skills, Nancy set him up with Ann. They went out on exactly one date that ended chastely, and awkwardly, after too much sake at dinner.

Ann remained single and struggled with alcohol abuse until she was told to quit or risk dying. In 2009, she got her drinking under control. And then, in 2012, Wetter materialized at a book signing for the Wilson sisters’ memoir. This time, he and Ann made a connection.

She was charmed by his ability to cite philosophy and drawn in by his blunt and confrontational manner. They married in 2015.

“This is a person who is free,” Ann said of Wetter. “It doesn’t matter how many people say, ‘Hey, buddy, come on, you better rein it in.’ He believes the ultimate act of friendship and love is to tell the unvarnished, transparent truth, always.

“And that’s nice,” she added. “But, you know, it isn’t always the most comfortable.”

A few months after they were married, the family gathered for Thanksgiving. Nancy and her second husband, Geoff Bywater, then the head of music for Fox Television, were there, along with Nancy’s teenagers. One of the boys made a joke about karate-kicking a girl at school who annoyed him. Wetter didn’t like it.

“He reached across the table and he grabbed a hold of him and went, ‘You do that, and you’ll be acting like a little bitch,’” Ann recalled. “And those are words that never get said at the Wilson table.”

Many in the Wilsons’ circle were alarmed. “That’s where I wrote him off forever,” said Sue Ennis, a childhood friend and one of their most valued songwriting partners.

The tour bus incident came nine months later. According to a police report, Wetter had warned the boys not to let the dogs out and became enraged when one unintentionally left the door open. He punched one and put his hands around the throat of the other, according to the report. The boys fled and called 911. Wetter eventually pleaded guilty to two counts of fourth-degree assault.

The incident remains an unresolved flash point for the Wilson sisters. They disagree on how it was handled and what went down. In that same year, Ann and Wetter left the sisters’ West Coast hometown and resettled in Florida.

Ann’s management team issued a statement to The Washington Post suggesting that Wetter’s behavior could be linked to a loss of blood flow to his brain after a carotid artery suffered a blockage and that with surgery and therapy, his “medically diagnosed anxiety and rage episodes are more controllable.”

But in a recent Zoom interview, Wetter sounded unrepentant. He discussed his abusive childhood home and barrage of recent health issues. Yet he continued to gripe about Nancy’s family and seemed unconcerned about how the tour bus incident affected the Wilson clan.

“I don’t want to be a part of manipulating some fairy tale relationship or being a part of it,” he said. “If they want to talk to each other, they totally can.”

In early March, Nancy was sitting in the dining room of her home north of San Francisco, talking about the last few “super-scarring” years. She missed her sister and was convinced that Wetter had moved them to Florida to isolate her. For a time, they barely spoke. But they had begun to text again.

She had rebuffed Frey’s efforts to revive Heart in 2021. What even was Heart at that point? The band that Nancy loved touring with in 2019, or the new group of Nashville players that Ann had bonded with? Unable to agree, they turned to their own projects and separate tours. Was there any chance that this new Heart tour could work?

“I think it boils down to who Ann wants her village to be,” said Nancy. “Where’s her comfort zone?

She recognized by now that her comfort zone was different. That the kind of swaggering personalities with whom Ann found ease — her husband, her manager Frey — triggered bad memories for Nancy, a throwback to the power dynamics and control battles of their Wilsher days.

Three thousand miles away, Ann nursed her own wounds. She felt abandoned. Why didn’t anyone come to visit her in Florida? She missed the company of her sister and their old collaborator Ennis. She understood that it would not be easy for them to come stay in Wetter’s home.

But “we could get a hotel for the afternoon of songwriting or whatever,” she said. “I would like to hang out and laugh with them, for sure.”

Ultimately, though, Nancy relented.

“I love being in the band Heart,” she explained. “It’s the thing me and Ann built together. And it’s a beautiful machine. A big metal horse, that gets a lot of attention. Ann Wilson or Nancy Wilson separate — not nearly as many people are interested or come out to see that, because it’s not Heart. So, I mean, the chance to do Heart again, despite, you know, whatever the static on the outskirts, the periphery of it all, I don’t care about. I just want to do the Heart thing.”

Last summer, Nancy flew to Nashville to spend time with her sister and met Tripsitter, the band Ann wanted to hire. Everything clicked. Guitarist Ryan Wariner was awed by Nancy’s acoustic playing on 1978’s “Mistral Wind,” which Tripsitter had played countless times with Ann.

“But all of a sudden, there was that intangible thing,” he said. “That Nancy thing.”

“I think it’s her right hand,” said multi-instrumentalist bandmate Paul Moak. “She’s got this gypsy, flamenco strumming pattern that, it doesn’t matter what song we’re playing, it’s her own style.”

And so this new incarnation of Heart scheduled four concerts for the end of 2023 as a dry run for a larger tour.

“We weren’t sure what the future was going to hold,” said bassist Tony Lucido. “So we went into those shows with the attitude of, let’s just do the best we can. If this is the last time they play together, let’s make the show count.”

Even Frey, who had clashed with Nancy and her management team over the years, found himself delighted. “Nancy singing with Ann is like Keith singing with Mick,” he said. “It’s the secret sauce. I didn’t realize that until I heard it.”

Some peaceful sort of routine seemed to have taken hold by the time the tour arrived in Tampa.

Nancy’s husband lingered in her dressing room until it was time to catch Cheap Trick’s opening set. Frey wasn’t there — Ann had suggested he work from home to reduce backstage tensions — but Nancy’s manager wasn’t there either. Wetter hung back on Ann’s tour bus but came out to watch the show from the soundboard.

“Our family was a really big togetherness family,” Nancy had mused back in California. “But maybe now we have to compartmentalize our actual today family, in a different way, and concentrate on the eye of the hurricane, where it’s peaceful and creative. Let the politics fly around and the cows fly through the air.”

The sisters emerged from their respective dressing rooms a few minutes before showtime to sit together in a small tent backstage. Then the lights went down.

Heart in 2024 is exactly what it should be. Ann and Nancy Wilson stand side by side as they open with “Bébé le Strange,” the joyous 1980 groove that marked their departure from the Fishers. They do all the hits, from “Barracuda” to their first No. 1, “These Dreams.” They dive into album tracks, from their wistful and melodic “Dreamboat Annie,” to Ann’s melancholic 2023 solo song, “This is Now.”

And when it is over, the two sisters sit together until nearly midnight, laughing about how much better this has gone than they expected and how silly those sanctuary zones were. Even though they don’t say it, they have rediscovered the real sanctuary.

Alice Crites contributed to this report.