Two disparate, promising series have their debuts tonight, in a time slot where it will be tough to get a foothold.

The better of the pair, “The Unit,” comes from two highly decorated creators in their fields: controversial playwright David Mamet (“Glengarry Glen Ross”) and TV producer Shawn Ryan, known for FX’s intense “The Shield.”

“The Unit” is a throwback, about a special-forces military outfit that takes on secret missions against clearly defined “bad guys.” There are a few gray areas here, making it perfectly in lockstep with the current atmosphere in this country.

The series splits time between the men in the field and the families they leave behind. Standouts in the cast include Dennis Haysbert (“24”) as team leader Jonas Blane and Regina Taylor (“I’ll Fly Away”) as Jonas’ wife, Molly, who serves as den mother for those on the home front.

Whatever viewers may think of its politics, “The Unit” is riveting TV. Quick cutting between the suburban-looking base homes and jungles in the Third World is jarring, but works to establish the dichotomy of these soldiers’ lives.

“Sons & Daughters” is another, quite different type of family series. This comedy is partly scripted and partly improvised, and will feel all too real for many viewers.

At its heart is Cameron, played by co-creator Fred Goss, who starred in Bravo’s “Significant Others,” a similar but superior show barely seen during two seasons.

The series revolves around Cameron’s extended family, including his mother, Colleen (Dee Wallace), stepfather Wendal (Max Gail), sister Sharon (Alison Quinn) and stepsister Jenna (Amanda Walsh) and their clans. “Sons & Daughters” has a painful quality, as it tackles such topics as relationship problems, finances and blended families that will hit home with many.

Both of these series face an uphill climb, going up against quality programs such as “House” and “Scrubs” and freshman darling “Everybody Hates Chris.” Let’s give “The Unit” the edge, as the drama figures to jibe well with CBS’s older-skewing audience. (Dale McGarrigle, BDN Staff)