Carla Duren and Jessica Wortham in “Marginal Loss” | Photo by Dana Rogers

For Americans of a certain age, the attacks on 9/11 are the defining world event of our lives.

While we’ve seen various film and TV makers replay those moments in action-adventure terms, few, if any, representations of the aftermath, particularly the survivors, have revisited the days following the attacks as quietly and thoughtfully as “Marginal Loss,” the second play from Actors Theatre’s 42nd annual Humana Festival of New American Plays.

Deborah Stein’s play takes place over eight days, Sept. 13-20, in a warehouse in New Jersey where three survivors from the financial firm Lippman Kennedy are trying to piece back together the business records of the company that were destroyed in the Twin Towers. Helping them is young, ambitious temp Margaret (Carla Duren).

Armed only with a dial-up modem computer that shares a line with their only phone, boxes of a disorganized paper trail and yellow legal pads, they’re charged with reminding clients that the firm is still in business, despite the catastrophic number of deaths the office suffered.

All three employees are alive essentially due to dumb luck.

John (Ted Koch) was dropping off his kid at school. Allegra (Nancy Sun) overslept because she over-imbibed the night before. Cathy (Louisville’s Jessica Wortham making an awesome return to Actors Theatre) was being picky about muffins.

An unspoken survivors’ guilt hangs heavy over the characters and colors their range of emotions throughout the play.

As many people experience after a tragedy of this magnitude, sometimes the best balm for the soul is feeling useful. When Margaret introduces herself to John and Allegra, she’s quick to inform them that she gave blood at Ground Zero after the attack.

The three Lippman Kennedy employees cycle through what “being useful” means at any given time. They know they’re not just trying to save the company to save the company — they’re trying to save the company so the company can prop up the families of employees lost in the attack.

The actors all delivered solid performances. Koch, who has an impressive resumé of TV and film experience, delivered the most complicated range of emotions, and when his John finally crashes, it’s heart-rending. Duren’s transformation from naive and eager temp to full member of the team is a dramatic one (and kudos on her for the quick costume change).

Andrew Boyce’s scenic design also is one of the stars of the show. The hyper-realistic warehouse setting kept pulling my eyes from the action on stage to the perfect little details that could have easily been overlooked — the water-stained drywall panels, the tangle of extension cords in the corner, the Styrofoam packaging for a computer that some worker probably saved “just in case.”

Despite the thudding dullness of the warehouse — or perhaps because of it — Boyce’s work on “Marginal Loss” is one of the most instantly memorable set designs I’ve seen in a while.

Carla Duren and Nancy Sun in “Marginal Loss” | Photo by Dana Rogers

Meredith McDonough’s extraordinary direction borders on choreography at times, as the characters juggle phone calls and papers and talk over each other in an effort to put the company back on track. I have come to look forward to any play McDonough directs, and she has directed some of my favorite performances at Actors Theatre.

While “Marginal Loss” isn’t up there with McDonough’s production of “Airness” last year (I could literally talk about “Airness” for days), it’s good — really good.

And for those of us for whom the days after 9/11 are forever etched as a grim turning point in our lives, the play is a gut-punch of a reminder of what we did to feel useful, to comfort others and to care for ourselves after everything changed.

“Marginal Loss” continues through April 8. Tickets start at $25.