Left for Dead — Paul Engleman

It is December 1972. J. Edgar Hoover is dead, Richard Nixon has been newly reelected, and Private Investigator Mark Renzler is just settling in for another miserable Christmas season in New York City.
But even this dismal prospect fades when he is contacted by a friend of a friend in need of his help. Harmony Rollins, a blaxploitation film actress and star of the recently released Sister Shamus, is worried about her brother Harpo. An ex-Black Panther, Harpo was involved in the break-in of an FBI office and may be holding documents that the FBI doesn't want released to the public. Since the collapse of the Panthers, Harpo has been deep underground and was not in contact with his family until he called Harmony ten days ago, scared for his life and frantic that his cover had been blown. When Harpo doesn't pick up the getaway money she wired, Harmony turns to Renzler. Now Renzler must navigate through the wilderness of the fractured and paranoid radical left to find his man - or it will be a very un-Merry Christmas for all.