(NBC) — Friday on “Dateline,” after Emory University student Shannon Melendi disappears from her off-campus job, investigators receive a mysterious phone call that changes everything.

Here is a preview of Dennis Murphy’s report:

Shannon missing. It was beyond all imagination. From the roommate, a rough timeline emerged. Shannon was supposed to be in her dorm on a Saturday night. But when she still wasn’t home by Sunday morning — her roommate started to worry.

YVONNE MELENDI: She said, “where is she?” so she went looking for her. The first thing she did was went to the softball country club–

Shannon worked part-time at a softball field — about five miles from campus. The roommate headed out to look for Shannon with two other friends. But they missed the entrance to the softball field parking lot — and when they turned around they spotted something.

YVONNE MELENDI: She saw her car parked at a convenience store–

LUIS MELENDI: Gas station.

Shannon’s black Nissan — unoccupied and parked at the far end of a gas station.

DENNIS MURPHY: She was as proud as she could be of that car,

MONIQUE MELENDI: Yes, she was. She lov– she loved her car.

DENNIS MURPHY: What was concerning about the way the car was found, what condition it was in?

YVONNE MELENDI: It was unlocked, keys in the ignition.

Watch “Dateline: Shannon’s Story” at 10 p.m. on NBC4.

“Dateline NBC” is the longest-running series in NBC primetime history and is in its 30th 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.