The set of “The Third Army” is harsh. Under the lights it is simple, dark and cold. But when the lights go down between scenes, it shifts, as if by magic, revealing an impossibly complicated puzzle of angles, twists and dead ends.

Joe Sutton’s text matches Christine Jones’s set work flawlessly. At first glance the play seems straightforward. The audience is prepared to view an epic struggle between commercialism and the integrity of a small town. But as soon as the first scene ends, we are awakened to the reality that the show is about something more sinister, something both deeply buried and deeply personal.

The first scene sets Pavel Marek (Neil Maffin), the conservative young mayor, against industrialist Lubo Brodsky (Jan Triska) over the renovation of a nuclear power plant in Marek’s town. Diane Brodsky (Meg Gibson), Lubo’s wife and Marek’s lover, soon gets entangled as well. When the lights dim, the set evolves swiftly and strangely, laying the stage for an intense interrogation scene between Allison Crawford, played by Carla Bianco and Patrick Husted, who plays Barry Axelrod. At the close of the second scene, it is difficult to tell who was the real inquisitor.

With all of his characters introduced, Sutton begins to weave a complex narrative. The audience sees all that happens in the present but is forced to wonder about the sinister past. Love, treachery and betrayal rear their heads in the twisted plot threads that ensnare each character.

The show is truly captivating until the very end. As the plot develops, it becomes increasingly clear that characters are motivated by something far deeper than the desires that they display. Audience members are drawn in by this mystery as Sutton gives out the pieces of the puzzle one by one.

However, in the final scene, the play’s mystery unfolds and is laid neatly on the table, repeatedly. Sutton loses his sense of suspense as the play makes a dramatic shift from intense psychodrama to a feel-good Scooby Doo ending. This scene does not carry the overwhelming sense of melodrama that dominates the rest of the play, so it seems out of place and superfluous.

Greg Leaming, the director, pushes the limits with his dramatic music and lighting, but is successful with his actors. Triska’s Lubo is fascinating at every moment that he is on stage, and Meg Gibson is also a success as the fragmented Diane. Husted’s Axelrod is harder to stomach, with abrupt emotional falterings that could have been handled better.

Jones’ set is both fascinating and functional. It changes completely from scene to scene and uses minimal furniture. The gray sliding backdrops are all that is necessary to create a believable palace, office, country house and telephone booth.

The Third Army

Long Wharf Theater

Jan. 10-Feb. 11

Tickets: 787-4282/ 800-782-8497