Four actors do the work of five times as many in Bedlam theater’s splendid “Saint Joan.” And darned if the results don’t quintuple the dramatic resonance, too, of George Bernard Shaw’s drama of a spiritual determination so relentless that it rattles the confidence of a hypocritical medieval European church and aristocracy.

Bedlam’s artistic chief, Eric Tucker, is the director who mounted a hugely popular adaptation of “Sense and Sensibility” at Folger two years ago: If you saw it, you might recall Tucker’s innovative, highly mobile staging as a kind of Jane-Austen-on-wheels. For “Saint Joan” at the Folger — a revival of one of New York-based, six-year-old Bedlam’s first productions, which visited Olney Theatre Center for a short run in 2013 — Tucker casts a quartet of actors in a sprawling play that has slots for as many as 27. The current Broadway revival starring Condola Rashad features 19.

The demands Tucker’s conceit places on his tiny troupe are formidable. Still, the parceling out of parts and the pivoting from character to character are so deft — in some cases, actors trade off the same role in mid-scene — that you never have any problem figuring out who is who during more than three hours of storytelling. Only Dria Brown, as a compellingly full-throated Joan, plays a single character. Tucker, Edmund Lewis and Sam Massaro delightfully divvy up everyone else, from the churchmen Joan infuriates to the French soldiers she leads to the English nobles she freaks out, with her claims of hearing the inspirational voices of the saints.

So don’t be daunted by the evening’s length. There’s wisdom and wit in abundance in this outing with Shaw’s famously disputatious 1923 play, far more even than in the Broadway revival by the Manhattan Theatre Club. Tucker encourages the actors’ instincts for animating Shaw’s entertaining debates: Is Joan a divinely sanctioned visionary or simply a military savant, as she leads the demoralized French to victory against the invading English? As Shaw makes plain, Joan’s piousness lays bare the self-serving pieties of the clergy and nobility. Does her insistence that she has a direct channel to God in 15th-century France, he asks, threaten rebellion against the primacy of the Catholic Church? Is her appeal to the adoring common folk awakening a dangerous nationalism that could topple the feudal order?

The provocative questions swirl in lively fashion in Tucker’s production, whose energy is bolstered by the director’s bottomless basket of staging ideas, helping to break down an audience’s resistance to Shaw’s sometimes ornate language. The great scene, for example, in which Joan is portrayed as turning the tide of the battle for Orleans by beseeching God to shift the winds, allowing the French to approach the English by raft on the Loire, is rendered as exuberant child’s play: An electric fan switches on, and the bubbles that one of the actors blows waft charmingly across the stage in the direction advantageous to the French army.

If I were to see this “Saint Joan” again, I’d request one of the seats on the stage reserved for 20 or so fortunate theatergoers. The stagecraft is meta-theatrical makeshift: Music emanates from little cassette players, and the set consists of a few crude wall panels and a large, draped canvas; some of the costumes look like thrift-store bargains. But Tucker is like the Bear Grylls of stage conjurers: He knows how to survive on the barest of resources. And those onstage get to gaze closely — and shift repeatedly — as the story unfolds. You’ll have to see for yourself how this occurs.

The joyfulness of the performances and the humor the performers find in Shaw’s tart observations build a surprisingly lighthearted spirit into the evening, which may be why this “Saint Joan” doesn’t feel as if it’s a tiring sit. We are naturally curious, too, about this enigmatic central character, a woman insisting she belongs fighting beside men in a time when that was not only outrageous, but also an invitation to charges of heresy. Tucker’s band of players may be tiny, but they succeed unerringly in their quest to show us Joan as an unfathomable tower of strength.

Saint Joan, by George Bernard Shaw. Directed by Eric Tucker. Lighting, Les Dickert; production stage manager, Diane Healy. About 3¼ hours. $30-$79. Through June 10 at Folger Theatre, 201 E. Capitol St. or 202-544-7077.