"Boesman and Lena," Athol Fugard's excruciating drama of a South African couple wandering in a bitter alliance with each other and their arid world, is being given a powerful production at the Source Theatre.

The two, who are "coloreds," and thus third in the four-level hierarchy of apartheid, scratch out lives of barren despair, living in shacks made of discarded cardboard and tin, and eating what they can catch or buy with money earned from selling discarded bottles. They move because of circumstance--a white man is angered and knocks down their shanty, or a white master dies and leaves them homeless, carrying their possessions on their backs and trudging barefoot from area to area, in a 20-mile circle of pain.

Boesman and Lena cannot live without each other, although he has turned his bitterness on her, beating and blaming her without cease. His life has wrung him dry of compassion or tenderness, but she cannot let go of her need to be heard, to care, or to have human contact. When a stranger appears, a "kaffir" who is lower than they on the apartheid scale, she adopts him almost like a pet, sheltering him and talking to him even though he does not speak her language and indeed barely speaks at all.

Like many Fugard characters, they are isolated, cut off from a world that is spoken of but does not exist on stage. They are without connection to time or space, as the dehumanizing system under which they live in effect negates their existence. Director-designer Robert Thurber has used the Source's small, box-shaped stage to effect, without trying to disguise its innate claustrophobic atmosphere. There are times when the play could have used a stronger guiding hand, however, particularly with Michael Elliot Hill, whose Boesman could be even stronger with a little restraint. And there are times when the production becomes too static, almost as though it is too burdened by the despair it is trying to create.

Sylvia M'Lafi Thompson is stunning as Lena, reaching the many levels the play demands. Keith Johnson is surprisingly powerful as the nearly mute stranger--surprising because it is rare that a role so stripped of normal acting demands communicates so much.

The show plays through July 3.