How time flies. “Murder One,” which followed a single trial over an entire season, felt enormously ambitious when Steven Bochco introduced the series 20 years ago. Now the show plucked from its rib, “Murder in the First,” returns to TNT for a second season as a solidly crafted if mostly undemanding piece of summer entertainment, shifting to a new high-profile case with a ripped-from-the-headlines quality. Fast-paced and tense, the serialized construct isn’t a bad viewing option, even if it’s unlikely to rank first on many must-watch lists.

Taye Diggs and Kathleen Robertson are back as intrepid Bay Area detectives English and Mulligan, who almost immediately stumble upon a stop-the-presses case: Two teenagers shoot up a school bus, with one taking flight and triggering a massive manhunt, as questions of what motivated the pair slowly come into focus.

Morbid echoes of Columbine notwithstanding, there are new twists to the search, starting with the fact that the kid’s hacking skills lead one frustrated cop to describe him as “a homicidal Edward Snowden.” On top of that, Mulligan still faces nettlesome domestic issues, like her colossal screw-up of an ex-husband and what to do in overtime situations when her young daughter is left at school.

The premiere, written by co-creator Eric Lodal (who subsequently left the series), doesn’t exactly bring much nuance to the material, with the teen mastermind described as a sociopath — and that’s by his parents. The cast, meanwhile, welcomes several new members, among them “Entourage” alum Emmanuelle Chriqui, who somehow manages to look distractingly gorgeous, even by TV standards, in those unflattering uniform blues.

Notably, the first season — which dealt with murders linked to a young Silicon Valley mogul — labored a bit to keep dishing out red herrings, and after events in the second hour here, there are few clues as to how Bochco (whose son, Jesse, directed the first two installments) and company will extend this latest premise for another 10 episodes. Still, the beauty of centering on one case is that it offers the promise of closure, bringing serialized urgency to TNT’s meat-and-potatoes procedural formula.

There’s also some benefit, as well as an inherent limitation, in the continuity of casting. Unlike, say, “True Detective,” having Diggs and Robertson reprise these fairly nuts-and-bolts roles — focused on the crimes at hand, with the occasional nod to their work-life issues — spares the producers from the anthology format that requires basically creating an entirely new world under the same banner.

How well that meshes with the strategy TNT intends to pursue under new management remains unclear. But if the second run of this utility player mirrors the performance of the first, English and Mulligan should be prepared to patrol the streets of San Francisco a while longer.

TV Review: ‘Murder in the First,’ Season 2

(Series; TNT, Mon. June 8, 10 p.m.)

  • Production: Filmed in Los Angeles and San Francisco by Steven Bochco Prods. and TNT.
  • Crew: Executive producers, Steven Bochco, Eric Lodal; co-executive producers, Jesse Bochco, Jonathan Abrahams, Robert Munic; producers, Caroline James, Daniele Nathanson; director, Jesse Bochco; writer, Lodal; camera, Michael Mayers; production designer, Bruce Robert Hill; editor, Tim Tommasino; music, H. Scott Salinas; casting, Junie Lowry Johnson. <strong>60 MIN.</strong>
  • Cast: Taye Diggs, Kathleen Robertson, A.J. Buckley, Emmanuelle Chriqui, Laila Robins, Mo McRae, Mateus Ward, John Cothran, Raphael Sbarge, Lombardo Boyar, Ian Anthony Dale, Currie Graham, Mimi Kirkland