Greetings from Ventnor City (a Meg Daniels Mystery) by Jane Kelly
A woman recognizes Meg as the amateur sleuth who recently solved a mysterious disappearance from the 1960s, and she asks for help in learning the fate of the sister she last knew as a 19-year-old who ran away from her Ventnor home in 1968.
As they retrace her steps—and Meg gets a taste of the rock star life—they discover that there might be a sinister reason the trail has been cold for so long. Was she a rebellious teenager who got swept up in the counterculture and broke free of her restrictive family? Or did someone want her out of the way... permanently?