The two main characters in "Sunshine," William Mastrosimone's gritty and darkly funny one-act play that closes the season for Dark & Stormy Productions, have a manic edge to them.

The title character (Sara Marsh) is an exotic dancer who looks like she's gotten a bad batch of street drugs. We see her knocking urgently on a door, bobbing around with one foot bare, the other in a high heel.

It turns out Sunshine, battered and bruised, is fleeing an abusive husband. She takes refuge in the apartment of Nelson (Nels Lennes), a paramedic who appears to be quietly suffering from PTSD. He's curt and brusque, with little sympathy for a woman he initially regards as a prostitute. His jaundiced view of the world comes from seeing too many people dead or dying.

But these two souls, roiled by their psychological traumas, have more in common than it seems. Their trades both involve the human heart.

Sunshine works the fantasies of lonely men, including Robby (Tony Sarnicki), a feral college student. She knows the right things to say to the simple saps who are her regulars, even if her sweet nothings are generic and false.

Nelson helps to resuscitate accident victims, bringing them back to life — however diminished that existence may be. He wonders if it might be more merciful to let some of them die.

Sunshine and Nelson could be a match, in short, except for the fact that each is married to someone else who is, literally and figuratively, out of the picture.

Director Mel Day staged Mastrosimone's "Extremities" this summer for the same company with visceral impact. That show, about a would-be rape victim who turns the tables on her attacker, indicted larger societal issues, including violence against women and the practice of putting victims on trial.

"Sunshine," set in Providence, R.I., in the 1990s, is more of a character study from a time that now seems far away. If Day's throttling production sometimes feels a bit dated, it's not just because of the props, including a corded telephone that's central to the action. It's also because in the age of the Internet, there are more efficient, less creepy ways for people to address their loneliness.

Still, "Sunshine" makes up some of that distance with acting that delves into the psychological gnarliness of the situation. Lennes, a co-founder of Huge Theater, is a big burly fellow who could clearly swing his weight around. But his character doesn't. Next to Sunshine, he seems restrained, even gentle, despite his churning distemper.

It is Sunshine, played by a petite performer who punches way above her weight, who brings a sense of menace to the 90-minute play. Marsh's character is all about manipulation, about getting under people's skin and working her will. There is calculation there — imagine Lady Macbeth as a working girl. But there's also a lot of guessing and clawing as this searching woman, who lives in the shadows, struggles to find a way to get her soul some nourishing light.