Though reality programming would have us believe that addicts, hoarders and real housewives of a county near you always perform their craziness, scripted television functions on the opposite assumption — that insanity percolates beneath the surface only to burst through for season finales. “Nurse Jackie” began as a vehicle for “Sopranos” virtuoso actress Edie Falco, but, as networks try to confront the crazy who walk among us (“Jersey Shore,” “Flipping Out”), cable and the women behind “Nurse Jackie” ask what we aren’t noticing when they walk by.

The season two finale of the hospital-as-second-home comedy (the Academy of Television Arts and Sciences’ label, not mine) showed Jackie’s husband Kevin and best friend Dr. O’Hara staging an intervention for the show’s heroine. The interaction, necessary after 24 episodes of Jackie’s pill-popping, left her perspective maddeningly opaque to even the audience. The third season premiere picked up where the intervention left off and maintained Jackie’s denial, perhaps because Edie Falco does “keep calm and carry on” so well. Unlike reality television, this season examines what happens when your family and friends make good on their intervention threats. Two seasons ago, we entered the world of Nurse Jackie Peyton in medias res, with pre-established friendships, lovers and habits; now, she must rebuild it all.

Jackie’s proficiency as a nurse often took a backseat to her volcanic person life, but now her job is all she has. Though the premiere establishes that her position at All Saint’s is secure, the new tenor of her relationship with Dr. O’Hara, the most skilled attending, leaves some of the hospital closed off to Jackie. She still knows how everything and everyone functions, as exemplified by her catching O’Hara at her favorite restaurant, but she runs into a new obstacle: the genuineness she boldly trades her deceitfulness for, fails. The narrative arcs of each season have been structured around roadblocks — how will Jackie get drugs without Eddie? What will happen to her daughter if Jackie can’t calm her? What should Jackie do with O’Hara’s money if Kevin has rejected it? It’s a problem that Jackie subverts with ingenuity and further performances.

In yet another roadblock, Kevin’s hot (in both senses of the word) mess of a younger sister plants herself in the Peyton home, herself having been dumped by her pilot boyfriend. I like that the sister will pose a threat to Jackie’s delicate domestic veneer. As Jackie works overtime to repair her relationships with her husband, her children, her best friend and her ex, the sister swoops in to earn their unqualified affection. I’m not enthused about the impending sexual competition over Eddie, Jackie’s secret former lover turned Kevin’s best friend, because it would represent a mash-up of two plots from last season: Eddie befriending Kevin and Coop stealing Sam’s girlfriend.

The centrality of deceit to the show’s conceit underlines its perspective on women in the workplace and the life of a nurse. Other portrayals of nurses in medical dramas, Jada Pinkett-Smith in “RN” and the legion of anonymous actors on “Grey’s Anatomy” spring to mind, describe them as unsung workhorses, while show runners Liz Brixius and Linda Wallem show the physical and emotional demands of that role. Shondra Wilson’s doctors have time to exchange witty repartee in elevators and to exchange STDs in the break room; Jackie hoards her free moments to fuel up, not slow down, with adrenaline coming from sex or Percocet. Jackie is not unlike Cristina Yang of “Grey’s,” whose absence from the hospital this season crippled the show’s narrative progress. As frustrating as it is to see Jackie and the writers gloss over the trauma of an intervention, perhaps the breakneck speed of the hospital environment necessitates it.

In its artificiality, “Nurse Jackie” seeks to convey a truth of the human condition so often diagnosed through alternative programming. From its whimsically animated titles to the tap dance sequence in season two, this show displays awareness of its status as a television show without slipping into omnipotence. The viewers are subject to the whim of the writers, who are apparently subject to this defiant heroine they have created.