‘In Plain Sight’ spends final season in the mommy zone

The hand that rocks the cradle has her finger on the trigger. Heavily armed mothers appear to be a trend. Ashley Judd went into action-hero mode Thursday night when her son went “Missing” on ABC. Friday night’s “In Plain Sight” (9 p.m., USA) returns with a mother sporting even more firepower.

Season four concluded with Mary Shannon (Mary McCormack) killing an assailant bent on murdering her partners and then going into labor in the very next scene. Will she learn to reconcile motherhood — make that single motherhood — with life in the witness protection racket? I’m not going to give too much away, but she’s already got the “protection” part of motherhood down pat. It’s the nurturing, multitasking and letting things slide that she’s got to work on.

The fifth and final season begins with a story out of “The Social Network” — if Facebook was founded by preppies linked to a Skull-and-Bones-like secret society willing to do anything (and kill anyone) to guard their secrets. And, as it turns out, the object of their homicidal ire has mother issues of his own. Lesley Ann Warren returns as Mary’s mother, Jinx, and she’s in full grandmother stride — as if to make up for every mistake she made the first time around.

• Also on USA, “Fairly Legal” (8 p.m., USA) enters its second season. Brash and sassy Kate Reed (Sarah Shahi) has the unenviable task of starring as a lawyer who hates lawyers and legal bureaucracy, and who sets her sights on making legal mediation sexy.

She lives on a houseboat and listens to loud music that doubles as the montage soundtrack to scenes of her struggling to reach justice and fend off the advances of creepy guys who find her irresistible. Unlike the breezy USA comedies “Psych” and “Monk” that got their starts on Friday nights, this show tries way too hard.

Tonight’s other highlights

• Second-round action in the 2012 NCAA Basketball Tournament (6 p.m., CBS). More games can be seen on TBS (5:45 p.m.) and TNT (6:15 p.m.).

• Daniel Radcliffe stars in the 2004 fantasy “Harry Potter and the Prisoner of Azkaban” (7 p.m., ABC Family).

• The 2002 documentary “Standing in the Shadows of Motown” (7 p.m., Sundance) profiles the “Funk Brothers,” the house band that created an iconic sound for the Supremes, the Temptations, Gladys Knight and the Pips and many more.

• Tom Cruise leads a band of elfin creatures in the 1985 fantasy “Legend” (8:15 p.m., HBO Family), directed by Ridley Scott.

• A recording artist offers help to a developer of music software on “Shark Tank” (7 p.m., ABC).

• Winter brings adventure to an end on the first season finale of “Bering Sea Gold” (9 p.m., Discovery).

• Every walk down the aisle has a particular personal style on the premiere of “Four Weddings” (9 p.m., TLC).

• Our hero sees an opening on “Spartacus: Vengeance” (9 p.m., Starz).