Infusing the audience with an overwhelming feeling of anxiety and depression, Charter Theatre’s presentation of Christopher Wall play “Couldn’t Say” thrusts the audience into the middle of an oppressive portrait that examines the role of time and loss in a failing marriage.

The play opens with a frosty blue light reflecting off a tangle of twisted metal that serves as the simple backdrop of the two characters, Liz and Ethan. They are stranded on the highway in the middle of the night after their car breaks down.

When Liz (Deborah Kirby) refuses to let her husband Ethan (Robert John Metcalf) leave her alone in the car and search for the inn where they are going, the two are forced to pass the time as they wait for someone to drive by and help them. As they struggle to make light conversation and assure one another that help will come, their talk turns to progressively darker topics that reveal a painful past and the cause of their current despair.

The root of Liz and Ethan’s marital and personal problems lie in the recent death of their 15-year-old son, who was hit and killed by a car after a three-day fling of drugs and alcohol. While Ethan is trying to forgive Liz for the death, which he believes is her fault, Liz has fallen over the cusp of insanity and believes she is still able to talk to her dead son.

The overall content of the play becomes painfully tedious as the audience follows Liz and Ethan on a roller coaster ride of fighting, anger, confessions and denied requests for forgiveness. The characters walk a precarious tightrope between sanity and insanity.

While there are admittedly a few lighthearted scenes in which the characters joke and tease one another, the effort to ease the tension and dark mood of the play does not provide long-lasting relief. Rather, the sarcastic and self-mocking humor becomes more of an outlet for nervous laughter as the scenes are cut short and promptly dive back into the undercurrent of distrust and pain that become the overlying themes of the play.

Despite the trying and frustrating content, the actors’ talent shines within the confines of their roles.

Both Metcalf and Kirby give performances that evoke sympathy for their characters and hatred and disgust for their lack of action and inability to communicate. They succeed in adding dimension to their deeply complex but static characters. But, there is a touch of overacting in some scenes as they struggle to overcome the flat content that hinders character development.

Even though “Couldn’t Say” reflects a poor choice by Charter Theatre, the Glaser-Luchs Studio Theatre of the National Conservatory of Dramatic Arts offers an intimate venue similar to the Lisner Downstage black-box theatre. Everyone in the small audience of about 60 is given an optimal view of the production performed without a bad seat in the house.

Included in Charter’s season lineup are Allyson Currin’s “Church of the Open Mind” and Paul Donnelly’s “The Taste of Fire,” which will run in January and May respectively. Tickets are on a pay-what-you-can basis with a suggested donation of $5-10 for students and $20 for frequent play attendees.