After ending its first season on an operatic high, Showtime's best series is perhaps understandably low key through the first few episodes of its return, or as low key as a program built around a serial killer who scratches his itch by dispensing vigilante justice can be.

After ending its first season on an operatic high, Showtime’s best series is perhaps understandably low key through the first few episodes of its return, or as low key as a program built around a serial killer who scratches his itch by dispensing vigilante justice can be. Michael C. Hall’s portrayal of the title character remains a towering achievement, one that eclipses the show’s other shortcomings and rough patches. Spiced with dark humor and oozing atmosphere, “Dexter” is the buzzworthy franchise for which the pay cabler has long pined.

Crafting a second season was no small feat, inasmuch as Dexter played cat-and-mouse with another serial killer throughout year one that turned out to be his long-lost brother. Dexter ultimately killed him to protect his adopted sister (Jennifer Carpenter), but the ordeal left both of them emotionally scarred.

Indeed, as the new season begins, Dexter finds himself strangely off his game, unable to perform even a perfunctory ritual slaying.

“My life’s been all Jekyll and no Hyde,” he laments in the show’s persistent voiceover, as lifeless as its hero is inside.

Meanwhile, there are new quarries to be caught, leveraging Dexter’s position as a blood-splatter expert for the Miami P.D.; and a new challenge to overcome, as evidence of Dexter’s past handiwork attracts an implacable FBI specialist, Agent Lundy (Keith Carradine, who played a serial killer himself, memorably, in the miniseries “Chiefs”), making Dexter the mouse again, and putting the audience in the strange position of fearing for this murderous protagonist’s safety.

Dexter also continues to date the emotionally wounded Rita (Julie Benz), though even that relationship begins to show signs of strain.

As with the first flight — which I initially reviewed unfavorably before being absorbed by the show — the storytelling becomes richer and more engrossing as the season progresses, including the arrival of a gorgeous woman (Jaime Murray) somehow drawn to Dexter’s hidden dark (as in a deep shade of crimson) side, as well as Rita’s suspicious mother (JoBeth Williams).

Some new wrinkles are less involving, mostly those that center on the politics around the squad room, which inevitably feel like a tepid distraction from the main attraction. As played by Hall, he approaches his hobby with clinical precision, constrained only by the “hurt only bad people” rules laid down for him by his late father (the always-welcome James Remar).

“Dexter” will never be everybody’s cup of tea, from the extreme close-ups in the blood-drenched opening credits to the uncomfortable sympathy that occasionally surrounds the serial-killer protagonist, largely due to Hall’s enormously charismatic presence.

Inspired by the novel “Darkly Dreaming Dexter,” this isn’t the kind of series that can run indefinitely, but the show’s brain trust has dipped back into the well and improbably fished out another bloody winner. For Showtime, it’s the stuff that dreams are made of, darkly or otherwise.

Dexter

Showtime, Sun. Sept. 30, 9 p.m.

Production

Filmed in Los Angeles by John Goldwyn Prods., the Colleton Co. and Clyde Phillips Prods. Executive producers, John Goldwyn, Sara Colleton, Clyde Phillips, Daniel Cerone; co-executive producers, Scott Buck, Melissa Rosenberg; producer, Robert Lloyd Lewis; director, Tony Goldwyn; writer, Cerone; based on the novel "Darkly Dreaming Dexter" by Jeff Lindsay;

Crew

Camera, Romeo Tirone; production design, Tony Cowley; editor, Stewart Schill; music, Daniel Licht; title theme, Rolfe Kent; casting, Shawn Dawson. Running time: 60 MIN.

Cast

Dexter Morgan - Michael C. Hall Rita Bennett - Julie Benz Debra Morgan - Jennifer Carpenter Sgt. Doakes - Erik King Masuka - C.S. Lee Lt. Maria LaGuerta - Lauren Velez Angel Batista - David Zayas Harry Morgan - James Remar Agent Lundy - Keith Carradine Gail - JoBeth Williams Lila - Jaime Murray
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