"The Crossing" by Michael Connelly. (Photo courtesy Hachette Book Group/TNS)

“The Crossing” by Michael Connelly (Little, Brown, 400 pages, $28)

In terms of police work, Harry Bosch has always viewed the phrase “the crossing” as that moment when the paths of a predator and prey intersect, putting in motion a horrific outcome.

But for Harry, newly retired from the LAPD, “the crossing” takes on other meanings in the superb 20th novel in Michael Connelly’s compelling series. The title also refers to Harry’s transition from cop to private citizen and, in a move he never anticipated, helping an attorney prove a man innocent.

“The Crossing” also works as an insight into adjusting to retirement. Harry learns that while he has often defined himself by his job as a detective, he can still make a difference, and that work, no matter how important, is not the sum total of a person. Connelly handles this retirement with aplomb and fits well with this series in which Harry has aged.

In “The Crossing,” Harry is asked by his half-brother attorney Mickey Haller (“The Lincoln Lawyer”) to prove his client innocent of the rape and murder of an assistant city manager. A former gang member, Da’Quan Foster, seems to have turned his life around. Although the evidence — including Foster’s DNA found at the scene — seems solid, Mickey is convinced his client has been set up. As Harry looks into the case, he uncovers incongruities that reveal the unsavory side of the police force.

One of the pleasures of a Connelly novel is how he delves into the minutiae of a police procedural, making the most mundane aspects of an investigation exciting. In this case, Harry uses his decades of investigative skills — and instinct — to follow the trail of an expensive watch. Those skills also come in handy as Harry deals with the fact that he no longer has the resources of the LAPD at his fingertips. Although he reaches out to his former LAPD partner Lucia “Lucy” Soto, he is wary of compromising her status in the department. Introduced in last year’s “The Burning Room,” Lucy is an intriguing character, and one we want to become a recurring presence.

Readers may be taken back a bit to find this iconic character without a badge, but Connelly proves he still has much to uncover about Harry. Harry’s lifelong “mission” of police work never wavers, even without his detective shield. Mickey may see evidence as a way to help his client, but for Harry, evidence will always be “a bridge to the truth.”

Watching Harry reinvent himself — as so many new retirees have had to do — brings even more energy to this series that never lags.

“The Crossing” again proves Connelly as a master of the genre.