The American Dance Festival has brought Martha Clarke back to Reynolds Theater, this time with a “work in progress.”  Clarke, who is this year’s Scripps Award winner, is collaborating with playwright Alfred Uhry on Angel Reapers, a dance with texts and singing. The songs are Shaker spirituals, sung a cappella by the dancer/actors, and the action involves the earliest American Shaker community, founded by “Mother” Ann Lee in the 18th century.

Shakerism began in England, where it formed as an off-shoot of Quakerism. Shakers live in close community, in group houses for the brothers and sisters. They believe in the equality of the sexes, but also in their physical separation. They eschew the ties of marriage, and require celibacy. Their religious practices include shaking, writhing, speaking in tongues and other intensely personal expressions of spiritual experience, and the more communal activities of singing and dancing. Clarke and Uhry use these Shaker beliefs and practices to craft a highly theatrical exploration of power, faith, longing, sex, rebellion and perseverance. Angel Reapers also looks at dance — this dance, any dance — as the spiritual practice it is, or can be.

The long string of “no” near the beginning sets up the tension: sisters and brothers must not, shall not, will not do this that and the other that might bring them into a physical life uncontrolled by work or religious stricture. There may be freedom in this tight structure for some, but it is certain sure that the opening laughter will soon give way to less happy emotions. This surety is not initially a dramatic problem. Clarke and Uhry keep the balance between spiritual expression and sexual repression on a taut wire, and draw it tighter and tighter through the circling dances that coil the men and women in opposite directions. Theatrically, this is the most satisfying yet of the season’s offerings of “dance theater.” The dancers are superb, and they can and do act. They also sing, beautifully, providing their own rhythmic accompaniment with their stamping feet. The lighting, by Christopher Akerlind, is wonderful, creating pools of comfort and joy under an oppressive low ceiling of darkness.

The first half of the 70-minute show seems finished, polished, its action driving its next action inexorably on. We know what must happen, yet the play is studded with visual and kinetic surprises. But somewhere past the middle, it lags, and the strangeness is no longer magical. By the time we got to the big incidents, I’d been yawning uncontrollably for at least 20 minutes. When the four men remaining in the community returned to the stage buck naked for what should have been an ecstatic dance (according to some of the text), at first I was relieved, as this should turn out to be the penultimate scene — and it was. But the dance grated: when clothed, the men had been strictly upright, straight in the spine, even when kicking and flinging arms, or carrying on in other ways. Naked, they hunched over themselves, and seemed more clothed than when dressed. Maybe their essential guilty nature was being portrayed; maybe I’d just had more than enough consideration of the criminalization of sex and love by religious power figures professing to know the will of God. At any rate, I had no sympathy left for Mother Ann’s curtain speech. However, I’d happily see this again when it is finished, and would recommend it for the first half alone.