Frank Hastings of the San Francisco Police is now picked for a top-secret assignment: the office of powerful Senator Donald Ryan has been receiving anonymous death threats--but, because of the Senator's serious heart condition, he himself must be kept in the dark while the FBI and the police team up to investigate. So Hastings starts quietly questioning the Senator's touchy staff and flaky family. . . till the Senator gets one of the threat-letters directly and asks Hastings to check out a young ex-con named Frederick Tharp. Is Tharp the threatener?. Yes indeed. And, while Hastings searches for him, the motive surfaces: psycho Tharp is (or thinks he is) the illegitimate child of the Senator and onetime starlet Juanita--now in the loony-bin. But when Juanita is murdered, along with a couple of others, the illegitimate-baby history turns out to be more complicated. . . with revelations that will surprise few readers of California mysteries about Senators, secretaries, and bodyguards. Still, middle-aged Hastings is one of the most engagingly unmannered narrator-cops around, especially when updating his problematic romance with nice divorced-mom Ann; so, even with a hand-me-down plot, this is above-average reading for devotees of decent, wry, plain-talking detectives.