But lowered expectations is not enough to account for the completely entrancing experience Theatre New Brunswick has given us with its third show of the current season. Stephen Massicotte's complex, thoughtful, sophisticated and occasionally beautiful script, coupled with a production which takes lots of chances and capitalizes on almost all of them, gives a pair of captivating actors the opportunity, well, yes, to tug at our heartstrings.

The story is, to be sure, simple. It is, however, enriched with a level of detail and imagery that allows us to become engaged in the characters and their relationship; even more important is the profoundly theatrical nature of the way we come to see it. It is told in cross-cut snatches in which chronology and geography become almost irrelevant; it is organized not so much as a narrative as a free-associated chain of scenes in which thunder becomes artillery, sandbags and feedbags are indistinguishable, umbrellas are rifles and a multileveled acting space becomes, well, whatever you want: a farm somewhere in Canada, a battlefield in France, a departure dock in Montréal where the troops sailing off to glory in the Great War wave goodbye to the world they know.

Massicotte's script structures all this, with its free-associated skips and jumps, its remarkably coherent imagery, and the strange and challenging requirement that the female lead play not only Mary, the romantic interest but also, simply by changing her stance and voice, the other romantic interest, the charismatic Sergeant Flowerdew ("Flowers"), who leads a cavalry regiment, including her Charlie, into the battle of Moreuil Wood -- all while barefoot in a white nightgown (all of it is, after all, her dream).

Constructed as that dreamscape, the play begins with Charlie explaining to us that "tonight is just a dream . . . it begins at the end and ends at the beginning." Between that and the end, ninety minutes later, as Mary reminds us that it's all been a dream, we're led through a deepening relationship, both between Charlie and Mary and between Charlie and Flowers, presented in fragments of dialogue using every inch of Denyse Karn's lovely, tilted, unbalanced set, and among the three large projection screens, punctuating and illustrating the action with a kind of visual counterpoint. The play begins with the partly narrated, partly enacted first meeting of the couple in a barn during a thunderstorm and the strangely erotic ride home, she behind him on a horse (this is -- like much else in the production -- achieved by an imaginative kind of mime: in this case the two of them standing balanced on a fence rail). Soon we're in a fantasy where Mary is waving goodbye to Charlie as he leaves for the war -- though, she says, "The strange thing is, I was never here. I was at home, in my room. I was never here with the people on the shore. This is not how we said goodbye. When Charlie sailed, I was two days away by train."

What happens next is strange and remarkable: Mary announces that, in the dream, she is Sergeant Flowers, and the conversations between Charlie and his superior officer have the weird doubleness of a superior officer comforting a lost and homesick recruit, while looking like a girl in a nightdress doing the same thing. From this point the action shifts seamlessly between Flowers and Charlie at war and Mary and Charlie, before the war, negotiating a delicate relationship, and dialogues which somehow happen outside either world -- for instance, as Mary reads aloud to Charlie, in some parallel universe, a letter she'd received from him. Both relationships deepen gradually into love, as Mary shifts back and forth instantly from herself to the imperious but increasingly kindly Flowers, like Mary, comforting Charlie and advising him.

As in almost any other treatment of the first World War, much is made of the constrast between the high ideals and naive fantasies of the recruits and the bleak reality of trench warfare, of the astonishing fatality rates and the blind stupidity of the higher commands. And, of course, the losses on the home front as the news of death and loss arrived. All this would be pretty much a sentimental cliché except for the remarkable fantasy at the center of Massicotte's script, that somehow time has been erased, and Mary knows both before and after the fact what happens, and that the friendship that develops in battle between Charlie and Flowers somehow stands in for the one so brutally truncated between Charlie and Mary. The moment when Flowers lies gravely wounded in Charlie's arms (but what we see is Mary, in her nightdress, reclining in Charlie's arms as she never will), offers us a remarkable theatrical image -- a kind of innocent, romantic homoeroticism that conveys quite powerfully the deep need for human companionship in the midst of battle.

The production carries all this off in one uninterrupted, seamless, dreamlike arc. The two actors are focused, engaged, and magnetically present from beginning to end. If there were moments when Raquel Duffy's Flowers carried a bit of Mary across the scene changes, perhaps it wasn't entirely accidental; if Andrew Bigelow's innocence and rural clumsiness seemed a little excessive, perhaps that was a choice as well. A great deal of the power of the production is generated by the subtle, effective lighting (originally designed by Bruce MacLennan, and here set up by Jeff Logue), the wonderfully timed three-screen back projected images, and the unobtrusive but lovely sound design. All of it adds up to one mesmerizing experience.

I need to say, however, that there is, after all, however, one serious problem with this production: Massicotte's script is in large measure about horses, as well as about the two relationships. Both involve horses -- Charlie teaches Mary to ride, and the equitation has a kind of powerful erotic charge; so, too, Charlie and Flowers are in love with horses as part of the cavalry brigade. The romance of the charge -- Tennyson's "Charge of the Light Brigade" runs through the script, and the production, as a sort of leitmotiv -- and in many ways the cavalry charge in the Moreuil Wood, which (in one view, at least) turned the tide of the war in 1918, is the climax of the show. It's where Flowers is killed, and in its aftermath, as Charlie finds his lost horse amid the carnage, that he is killed by an artillery shell (reminding us of his fear of the thunder in the play's first scene).

But there are no horses here: when Bigelow mimes leading and grooming and fondling a horse's mane, I wasn't convinced for an instant that there was a horse there. When he and Duffy ride together on the fence, it didn't feel like riding; when she is up on the horse and he's coaching her, I didn't believe in that horse, either. Massicotte's last stage direction -- after Charlie and Mary have said their final dreamy farewell, and he's enjoined her to "wake up, Mary, wake up," is "a single horse rides away into the distance." I wanted to believe that horse was riding away, and I didn't.

This may seem to be picking a particularly obscure nit, but to make these mimed horses more real would, I would argue, make this fine production even better. Even as it is, however, it serves to remind us that Theatre New Brunswick and director Scott Burke are capable of offering us a kind of experience that no other form -- not film or video, not fiction -- can offer. The remarkable double sense of being inside the story and knowing someone's telling it to you, of seeing someone who is at one and the same time an actress, a young woman in love, and the leader of a cavalry brigade, of having what you're seeing be the fierce vexation of Mary's dream and your own at the same time: it's why we pay to go to the theatre.