When a sheriff's detective shows up on former FBI man Terry McCaleb's Catalina Island doorstep and requests his help in analyzing photographs of a crime scene, McCaleb at first demurs. He's newly married (to Graciela, who herself dragged him from retirement into a case in Blood Work), has a new baby daughter, and is finally strong again after a heart transplant. But once a bloodhound, always a bloodhound. One look at the video of Edward Gunn's trussed and strangled body puts McCaleb back on the investigative trail, hooked by two details: the small statue of an owl that watches over the murder scene and the Latin words "Cave Cave Dus Videt," meaning "Beware, beware, God sees," on the tape binding the victim's mouth. Gunn was a small-time criminal who had been questioned repeatedly by LAPD Detective Harry Bosch in the unsolved murder of a prostitute, most recently on the night he was killed. McCaleb knows the tense, cranky Bosch (Michael Connelly's series star--see The Black Echo, The Black Ice, et al.) and decides to start by talking to him. But Bosch has time only for a brief chat. He's a prosecution witness in the high-profile trial of David Storey, a film director accused of killing a young actress during rough sex. By chance, however, McCaleb discovers an abstruse but concrete link between the scene of Gunn's murder and Harry Bosch's name:
"This last guy's work is supposedly replete with owls all over the place. I can't pronounce his first name. It's spelled H-I-E-R-O-N-Y-M-U-S. He was Netherlandish, part of the northern renaissance. I guess owls were big up there." McCaleb looked at the paper in front of him. The name she had just spelled seemed familiar to him.
"You forgot his last name. What's his last name?"
"Oh, sorry. It's Bosch. Like the spark plugs."
Bosch fits McCaleb's profile of the killer, and McCaleb is both thunderstruck and afraid--thunderstruck that a cop he respects might have committed a horrendous murder and afraid that Bosch may just be good enough to get away with it. And when Bosch finds out (via a mysterious leak to tabloid reporter Jack McEvoy, late of Connelly's Hardcover edition. 
