(NBC News) — Friday on an all-new “Dateline,” after the death of 44-year-old mother Stacy Feldman is ruled undetermined, friends and family join forces to piece together what happened.

“Dateline” correspondent Keith Morrison speaks to insiders on their seven-year battle for justice.

Here is a preview of Morrison’s report:

The celebration of Purim is one of the most festive Jewish holidays it’s an extra special one for kids — marked by costumes, carnivals, and special dessert treats called “hamentashen.”

March 1, 2015, was a big day: The Purim carnival at the Feldman’s synagogue. Bob said he dropped the kids off for religious school at 8:30 that morning and then the plan was for Stacy to pick them up at noon and take them to the carnival. But pick-up time came and went.

SUSAN ALTMAN: And she didn’t arrive, and so the school was calling her. And she didn’t pick up.

So, they called Bob. He fetched the kids and took them to the carnival. He said they all got home around 3 p.m. The shower in the master bathroom was running. Bob went upstairs.

SUSAN ALTMAN: And then he says that’s when he found her.

[911 call] BOB FELDMAN: What do I do? Please, help me!

What happened to Stacy Feldman? Watch Friday’s “Dateline: The Sisterhood,” on NBC4 at 9 p.m.

“Dateline NBC” is the longest-running series in NBC primetime history and is in its 31st season. Dateline is anchored by Lester Holt and features correspondents Andrea Canning, Josh Mankiewicz, Natalie Morales, Keith Morrison and Dennis Murphy.

Dateline is the #1 Friday newsmagazine and reaches more than 17 million people every week through its broadcast, and millions more through its social media platforms and podcasts.

The stories range from compelling mysteries to powerful documentaries and in-depth investigations. When major news breaks, they go to the scene, putting the pieces together to bring the viewer the full picture. And in every story they tell, they help the real people who lived the events share their journeys with the viewer.