Thomas Magill is the type of guy of whom people would later say, "He always seemed like such a nice young man." The cheery missionary at the center of Enda Walsh's "Misterman" seeks to spread God's word throughout the small Irish town of Inishfree, which he sets out to do daily after tending to his sick mother and visiting his father's grave.

But trying to get the message across can be so frustrating. When Solas Nua's satisfying production of "Misterman" begins, Thomas (Dan Brick) is standing in his Sunday-best vest and tie, with a big smile that is all cheek and brotherly love. But as he talks about his calling, Thomas starts getting a little annoyed. "Sin has become our religion, greed our communion, and evil is our God!" he bellows.

It's the first sign there are cracks in Thomas's benevolence -- and there are more to come. "Misterman" is only the second offering from Solas Nua, a company dedicated to contemporary Irish art that debuted this summer with another Walsh play, "Disco Pigs," which generally was well received. Both dramas are intense and short -- "Misterman" runs about 50 minutes -- although audiences irritated by the heavily accented baby talk of "Disco Pigs" will probably find this offering more accessible.

Walsh also doesn't care for sets. So Brick, the production's sole performer, does all the heavy lifting in the D.C. Arts Center's black-box theater, its small performance space adorned only with a swing and a suit on a hanger. Brick conjures other characters onstage, however, including the hunchbacked, tremulous old Mrs. O'Leary, who thinks Thomas so wonderful that she weirdly threatens to kidnap him, and Aidan, a fellow who uncomfortably tries to be polite when Thomas rallies for him to join his mission -- at least until he sees a racy calendar in Aidan's home.

In the hands of a performer as adroit as Brick, Walsh's succinct, compelling story really doesn't need much embellishment. Still, for such a spare production, "Misterman" does have some neat tricks.

Overhead pipes and Marianne Meadows's lighting summon a quite realistic rainstorm, and Chris Pifer's sound design makes us privy to some of Thomas's unseen misdeeds. Twice we hear recordings of conversations between Thomas and his mother. One tape is tender. The other conveys an argument and provides one of the performance's chilling moments, as Thomas listens and reacts to his earlier loss of temper. It's not Thomas's mother who is the agent of his undoing, however, but rather "an angel" named Adele whom Thomas falls for -- although we later find out that his ardor ultimately is unrequited.

Brick's choirboy appearance is the first step in creating an effective Thomas. Immutable niceness wouldn't do, though, and this is where Brick excels, morphing from loving to angry to unhinged, then back to benevolent. Those changes can occur in a matter of seconds, with Brick relying only on flickers of expression to reveal which Thomas is present. But come "Misterman's" disturbing, surprising end, there is no question which personality wins out.

Misterman, by Enda Walsh. Directed by Linda Murray. About 50 minutes. Through Nov. 20 at D.C. Arts Center, 2438 18th St. NW. Call 800-494-8497 or visit www.solasnua.org.

Dan Brick's adroit performance anchors a tale of zeal run amok.