In Book 1 - Death Before Coffee - Holly has recently returned to her hometown of Little Creek, Arizona. But it’s not until Book 2 or even 3 that we begin to unravel the story of her parents’ death. Something along these lines:
Holly has been quietly investigating the accident that killed her parents, suspecting that it wasn't entirely accidental. Using her tarot cards and connections at the bookstore and police office, she has been piecing together clues, but she's kept this quest for truth a secret to avoid worrying her aunt.
Who has the information or links to the truth about the accident And is that mystery person aware of Holly's investigation?
Still thinking.