It could be about a real - life event like a historical incident. For example, it might be about a war experience, where she heard stories from her grandparents who lived through it. Maybe it's about a local legend that has some basis in historical facts, like a mystery in her hometown that was finally solved and she's sharing the real story behind it.
It could be about a personal experience like a journey she once took. Maybe she went on a solo backpacking trip across a beautiful country, facing various challenges along the way such as getting lost, meeting interesting people, and having to adapt to different cultures. This kind of story is often based on true events as many people do embark on such adventures.
You can also try to find witnesses. If the story is about a local event, ask around in the community. There might be people who were there and can confirm or deny the details. Another option is to cross - reference with other similar stories. If it's a common type of story, like a haunted house story, see if there are other accounts that match the basic facts she presented.