“Southland” 10 tonight, TNT

For Detective Lydia Adams, “coming to work is the easy part of my day.” For another cop, whose home life is falling apart, work doesn’t begin to compensate. “I don’t have a second act in me,” he said.

“Southland,” one of the consistently best shows on TV, begins its new season tonight on TNT by doing what it has done for the previous four years: portray with unusual and convincing realism the lives of men and women of the LAPD.

Other shows may fall back on gimmicks by the time they hit their fifth season, something to reignite flagging interest, but “Southland” shows its pedigree in the season opener with a deceptively restrained day-in-the-lives of the characters portrayed by its core ensemble.

Adams (Regina King), who, as a single woman, agonized over having a baby last year, struggles to get out of bed now, feeling grateful her own mom is around to care for young Christopher while Lydia goes off to work. Officer John Cooper (Michael Cudlitz) kicked his addiction to painkillers and is physically back on his feet after back surgery, but still internalizing emotional struggles. He’s been seeing the same guy for a while, and the arrangement is fine with Cooper. But his boyfriend thinks that three years of “banging each other” ought to amount to a real relationship. Cooper just gets ready for a day on the streets of Los Angeles.

Officer Sammy Bryant (Shawn Hatosy) begins his day by meeting his ex-wife (Emily Bergel) in a parking lot to take their 2-year-old son Nate and hand him over to a babysitter so Sammy can get to work. His ex tries to goad him into striking her while she not-so-secretly records their encounter to use in their ongoing custody battle.

Officer Ben Sherman (Ben McKenzie), no longer the Hollywood pretty boy, takes his job much more seriously now, but still enjoys a good bash, especially if it’s being thrown to celebrate his recent award from the department.

The premiere episode follows the main characters through the day. Cooper is saddled with a new partner named Gary Steele (Derek Ray), who can’t help contrasting what it was like to fight in Afghanistan against being an LA cop. Adams is still partnered with Det. Ruben Robinson (Dorian Missick), who is married but continues to demonstrate genuine fondness for Adams, even if he can’t resist advising her that breast-feeding is much more beneficial to young Christopher than feeding him formula.

The driving strength of “Southland” is how each character’s life and personality are shaped by the job of being a cop, and, at the same time, how they almost take refuge in the job from challenges on the home front. Adams wants to be a good mother, but at the end of a trying day, she pauses at her front door and, seeing her mother inside trying to comfort a crying infant, holds back, trying to find the energy she knows will be required of her when and if she goes through that door. Cooper may be comfortable being gay, but that doesn’t mean he’s reached a level of peace with his demons that would enable him to be in a real relationship.

Yes, the cops solve crimes. Sometimes they make the right call in a situation; other times, they don’t. But as perfectly detailed and credible as the action sequences are, “Southland” is about character and benefits not only from superb writing (Jonathan Lisco for this week’s episode, Heather Zuhlke for next week) but by stellar performances by every cast member.

There isn’t a better cop show on TV right now than “Southland.”