[Caution: This story discusses sexual assault.]

Will & Grace has had no shortage of serious moments over the years, like that time Jack (Sean Hayes) revealed the depths of his own self-loathing by pretending to be straight for his homophobic mom or when Grace (Debra Messing) and Leo (Harry Connick Jr.) divorced. But no moment — not even that sad funeral for Rosario (Shelley Morrison) at the top of the revival season — got as heavy and intense as "Grace's Secret." In it, Grace reveals she was sexually assaulted as a teenager, and the episode just might give the prime-time sitcom another Emmy nomination to add to its pile.

Discover your new favorite show: Watch This Now!

Grace's story in "Grace's Secret" starts off simple enough: She's forced to go on a road trip with her dad Martin (Robert Klein) to visit her late mom's grave. You know how time with just you and the 'rents can go: plodding, repetitive, excruciating. Before Grace leaves though, Will (Eric McCormack) advises her to actually take an interest in Martin — learn his likes and dislikes, whether he's ever hooked up with a guy, that kind of thing — and things are going OK until they sit down for dinner. Grace's dad is frustratingly old school with the waitress (i.e., flirting and calling her pet names, which is totally inappropriate and condescending), which leads to a conversation about women's issues in the workplace. When Grace chastises him, he says, "Everybody's so sensitive nowadays," the go-to defense for jerks who try to defend their insulting behavior. "Sometimes I feel like men can't be men anymore — not with this hashtag 'not me' stuff."

PHOTOS: 25 Great LGBT Characters in Pop Culture Right Now

That's when things go nuclear. Martin chastises Grace for her work history, including the time she quit working for his friend Harry and stole cash from a drawer. And that's when Grace opens a wound that had been festering for decades. "The whole summer I worked for Harry I kept telling you he was creepy. What did you think that meant?" she says.

Still clueless (ugh), Martin dismisses what his own daughter is trying to tell him, figuring Harry was just being flirty (as if that was OK), that it was a different time (as if that was OK) or that she misremembered what happened — an egregious attack that diminishes sexual assault survivors and keeps rape culture alive. "No!" Grace shouts, "I remember!" With her voice rising, Grace unleashes a shocking and painful truth: Harry forced himself on her in his office, muffled her screams, kissed her and pulled down her pants. Grace doesn't even finish the whole story, but it sounds a lot like she was digitally raped — penetrated with fingers without her consent — as her father processes what he's heard. "I was 15," Grace says.

Robert Klein, Debra Messing; Will & GraceRobert Klein, Debra Messing; Will & Grace

It's a powerful moment, one made even more compelling by Grace's admission that she only told one person about the assault, whom Martin assumes to be Will. It wasn't, and the fact that Grace couldn't even tell her best friend what had happened is a testament to the burden sexual assault survivors can carry with them their entire lives.

Debra Messing's performance is like nothing we've ever seen from her on Will & Grace, and it's a moment that demonstrates just how relevant and urgent the show can still be, some 20 years after it ushered in an era of acceptance we take for granted today.

Will & Grace airs Thursdays at 9/8c on NBC.