On the afternoon of July 1, 1981, Los Angeles police responded to a distress call at 8763 Wonderland Avenue and soon discovered a grisly quadruple homicide, later compared to the gruesome slaughter at the Tate household at the hands of the Charles Manson family 10 years earlier. Ron Launius (Lucas), Billy Deverell (Nelson), Barbara Richardson (Wagner) and Joy Miller (Garofalo) were brutally murdered, and Ron's wife Susan (Applegate) was left in critical condition. The police investigation that followed - led by detectives Sam Nico (Levine), Louis Cruz (G.) and Mike Peters Gainey) - would unearth a seedy world of drugs and violence, ultimately revealing a motley crew from LA's underbelly including ex-con David Lind (McDermott), nightclub impresario Eddie Nash (Bogosian), the most unlikely of American heroes - porn legend John Holmes (Kilmer) - Holmes' estranged wife Sharon (Kudrow) and his teenage lover Dawn Schiller (Bosworth).