Dodge Mansion in Georgetown, where the alleged rape occurred during a 2016 Halloween party. (Google Maps)

Everyone knew.

A year ago at a Georgetown Halloween party, everyone knew something had happened to a young woman upstairs. A 21-year-old who screamed and then sobbed.

It happened during one of the hottest Halloween parties in Washington, at a place appropriately called Dodge Mansion.

Every year, multimillionaire Bill Dean hosts an annual bacchanal that features topless models in body paint circulating among a few hundred costumed guests. Last year’s event was wrapping up about 4 a.m. when some of the remaining partyers heard loud cries of distress coming from the second floor.

One guest followed the sounds into a second-floor bedroom and found a woman on the floor, naked and saying she’d been raped.

“I was screaming,” the woman said in an interview with The Washington Post last year. (The Post typically does not identify victims of alleged sexual violence without their consent.) She acknowledged that she had snorted cocaine before the attacker violently bit, grabbed and penetrated her.

Two women tried to help her, but witnesses said the alleged rapist came back into the room, threw one of the women against the wall and bashed the head of another woman against the floor.

About a dozen police officers filled the mansion, taking statements. Everyone knew the alleged attacker. He’d fled before police arrived. Everyone was interviewed, although the alleged victim did not want to go to the hospital for an examination. Instead, she went home and took a shower.

A year later, no charges have been filed. Police turned all their information over to the U.S. attorney’s office, which is still investigating the matter, said spokesman Bill Miller. He can’t comment on it, he said.

I haven’t lost hope that police and prosecutors will charge the alleged attacker. But why is this taking so long?

Is it any wonder that women don’t always report sexual assaults and harassment, knowing the doubts they’ll face and the prolonged ordeal that lies ahead?

Which brings me to Harvey Weinstein, the powerful Hollywood mogul who has been accused of preying on women for decades. Everyone knew, but no one wanted to do anything about it.

"I did tell people about it," actress Daryl Hannah told the New Yorker last week. "And it didn't matter." That's because, she said, women "are not believed. We are more than not believed — we are berated and criticized and blamed."

Being doubted, being blamed, being punished — this is what kept women silent for so long about Bill Cosby, Roger Ailes, Bill O'Reilly, movie director James Toback, former Amazon Studios executive Roy Price, former New Republic literary editor Leon ­Wieseltier, political journalist Mark Halperin and, of course, Donald Trump.

The allegations against Weinstein have set off a #MeToo avalanche that isn’t close to being over.

Nearly 150 women working in California's state legislature signed a letter last week describing years of sexual harassment, including lawmakers exposing themselves, groping and threats. The grievance system didn't work for any of those women, they said.

Hundreds of thousands — women you’ve probably sat next to on the train, eaten lunch with every day, collaborated with on a work project — have been sexually assaulted or harassed and never said anything.

Because even if you’re on the floor naked and crying, even if there are witnesses and police statements, you might be doubted.

And this phenomenon isn’t limited to Hollywood movies or Georgetown parties. It’s everywhere, from law firms to fast-food fry stations.

"One day, [my shift supervisor] Derek showed me a photo of his genitals. That was my breaking point," said Cycei Monae, who alleges that she was repeatedly harassed by her boss at a Michigan McDonald's. She was one of 15 women featured in a film by the activist group Fight for $15.

Rebekah Havrilla, the only female member of her bomb squad in eastern Afghanistan, was sexually harassed for months by her supervisor, she told lawmakers four years ago. But she kept quiet.

“One week before my unit was scheduled to return back to the United States, I was raped by another service member that had worked with our team,” she testified to Congress. “Initially, I chose not to do a report of any kind, because I had no faith in my chain of command, as my first sergeant previously had sexual harassment accusations against him and the unit climate was extremely sexist and hostile in nature towards women.”

Extremely sexist and hostile toward women. Everyone knows it’s time — beyond time — for this climate to change.

Twitter: @petulad