(Photo by Toni L. Sandys/ The Washington Post)

PHILADELPHIA — So this was what heartbreak would look like in 2016: a Capitals star sitting helpless in the penalty box, booked on a case of mistaken identity.

The scriptwriters had done it again, dreaming up  a four-minute double-minor on Nicklas Backstrom, who happened to be nearby when one of Ryan White’s teammates accidentally high-sticked him. The Flyers would score on the ensuing two-man advantage, Game 7 would do what Game 7 does, and this moment would be added to the list of Washington’s impossible-to-believe postseason woes. What’ll they think of next?

Only this time, the gut shot led not to a panicked, soul-rending collapse, but a 1-0, series-clinching win over the Flyers. With fans already choosing which shade of red pitchforks to rock at Game 7, the Capitals showed — what’s this? Resilience? They glanced at the latest punchline from the hockey gods and they nodded, same as they had after Friday’s onslaught on the Flyers net went unrewarded.

“People were a little bit panicky, and we weren’t,” Karl Alzner said after the win. “And that’s huge for this team.”

“A little bit panicky” might be an understatement. Logic said the Capitals were the better and healthier team, that they had dominated most of the first five games, that they couldn’t possibly lose four straight times to a Flyers team running on fumes and pretzel grease. Then emotion pulled logic’s shirt over its head and started whaling away. After the Capitals went 1-8 in their last nine chances to clinch a series, and after five straight Washington playoff series went the distance, how could you relax before this Game 6 torment? Without prescription assistance, anyhow?

And then came one of those classic did-that-really-happen Capitals playoff moments: Backstrom was banished for four minutes early in the second period, despite his stick not touching White’s face. Matt Niskanen was sent off five seconds later, giving the Flyers two full minutes with two extra men. If you didn’t feel history’s tingle then, your sensors must have been malfunctioning.

On the ice, though, players described something different.

“We’re not scared,” said Jay Beagle, one of the penalty killers who pushed aside the looming disaster. “No one’s worried.”

“I was just kind of in the zone at that point,” said Alzner, another penalty killer.

“It is what it is, and you just have to deal with it,” said Mike Richards, a third penalty killer.

“It was almost like we were cheering on the bench,” said T.J. Oshie, who had a front-row view. “That’s what it sounded like out there, high-pitched voice and all.”

Washington survived that interminable two minutes. Less than a minute after Backstrom escaped the box, he scored the go-ahead, puck-don’t-lie goal. The Caps withstood Philadelphia’s third-period push, and then moved into the next round. And if you’ll pardon a messy burst of narrative, they did so in a gutty style that has not always been their postseason hallmark.

Consider: This was the first time the Caps have ever closed out a series with a 1-0 win. It’s only the second time they’ve won a series with a shutout; the last came during their 1998 Stanley Cup finals run. The six goals they allowed to Philadelphia were the fewest they’ve ever yielded in a best-of-seven series. Their postseason goals-against average — a tidy 1.0 — is easily the best in the league. (Tampa and Anaheim are the only other teams below 2.0 a game.)

And the defining moment of this clinching victory was not an offensive highlight or even a Braden Holtby save, but Richards and Alzner and John Carlson and Beagle throwing their bodies in front of fate’s latest roundhouse, that misbegotten five-on-three disadvantage.

“If we don’t get through that, this building probably explodes,” Coach Barry Trotz said. “Once we got through that, I felt that we were going to find a way to win the hockey game.”

If you dreamed real hard, you could already see Backstrom’s phantom high-stick added to the montage of playoff suffering: Joel Ward’s 2015 goal waved off for goalie interference, Ward’s 2012 double-minor that led to New York’s tying and go-ahead goals, Alex Ovechkin’s 2010 Game 7 goal waved off for yet more interference, Esa Tikkanen missing an empty net in the 1998 Stanley Cup finals, Rod Langway getting sliced out of the 1988 playoffs by Pat Verbeek’s skate blade.

This year’s team, though, has spent six months talking about erasing adversity; Alzner called it the team’s “calling card.” They were the only NHL team to finish with a .500 record when giving up the first goal, and the league’s best third-period team. After falling behind to the Flyers in Game 4, they proceeded to out-shoot Philadelphia six periods in a row, piling up a massive storehouse of chances. By the end of a scoreless first period on Sunday, D.C. fans were reaching for paper bags. If you take them at their word, the Capitals felt just fine.

“When I first stepped behind the bench [in 2014], I felt that there was a little bit of nervousness in tight games,” Trotz said. “I think we’ve come full circle, where we’re comfortable being uncomfortable, if you will. … Sometimes you’re not going to get much, and you have to be patient. That’s probably where we’ve grown the most: in patience and poise.”

This was the owner’s message, too; “I sensed confidence,” Ted Leonsis said in a mostly subdued postgame locker room. “Even I felt stable.”

It’s one thing to feel stable against an inferior team. The next round, and a date with Pittsburgh, will offer a different sort of matchup. The Penguins excel by both traditional and advanced metrics. They had the most wins in the Eastern Conference over the second half of the season, and the East’s best possession stats. This would be a terrific conference final; it’s showing up two weeks too early.

That the Penguins arrived so early feels like a booby trap, another bad break in a 40-year run of them. But these Capitals have made it their mission to scoff at fate’s traps. Might as well take on another one.