A crown hovers over the stage in Opera House Arts’ production of William Shakespeare’s “Henry IV” like a flying saucer in some 1950s sci-fi movie, where no one knows if the aliens inside are friends or foes.

Is this the crown that will transform Prince Hal from a wild and wanton youth or is it the burden that keeps his father, Henry IV, from sleep as he cries, “Uneasy lies the head that wears a crown?”

It is all of that and more in Director Meg Taintor’s hands. She also wrote the script that combined the Bard’s two plays about Henry IV, who ruled England from 1399 to 1413. Taintor keeps the best of both plays but the production is flawed by its length — 3½ hours with an intermission on opening night last week — and a cast of three men and three women, playing about 30 parts.

Figuring out who the minor characters and are how they are related to the leads is difficult for all but Shakespeare scholars. More troubling is the casting of women in the major roles of Henry IV and Hotspur, a young nobleman who led an unsuccessful rebellion against the king.

Opera House Arts is known for its gender-bending casting and used it successfully last season in “Orlando” and “The Taming of the Shrew,” set in a women’s prison, in 2007. Jenifer Deal is more successful as Henry IV, especially in his death scene, than Esther Williamson is as Hotspur, mostly because Deal is so tall that she towers over everyone else on stage.

Neither woman consistently ambles, strides or confronts a rival the way a male would with an open invitation to do battle.

Williamson’s Hotspur behaves more like an angry, petulant teenage girl than a warrior with valid grievances. She thrusts out her chin, stomps her feet and waves her arms as if her mother took away her cell phone for a week rather than act like the man who would be King of England. As Hotspur, she is a constant irritation to the king, but never a threat.

Matt Hurley, a graduate of Bangor High School, is perfect as Prince Hal. He is always aware of that hovering crown. Hurley covets and rejects it in the same moment as Hal spends his days roaming the countryside with drunkards, thieves and whores.

They while away the hours swilling ale, pulling pranks, snatching men’s coins and bragging about their exploits. This behavior, the young prince says, will make his reformation when he’s crowned king, all the more admirable. “I’ll so offend to make offence a skill,” he says “Redeeming time when men think least I will.”

When Hurley does make that transformation, his eyes reveal that rejecting his old friends rests as heavily upon him as does the crown. He gives an engaging and princely performance that reveals the man inside the boy.

Curt Klump’s Sir John Falstaff is a lovable rogue who defines himself by his relationship to Prince Hal. Klump successfully mines Shakespeare of every joke and gag, yet he also imbues the character with a large dose of the sad clown. Klump gives such a multi-layered performance that when newly crowned Henry V rejects him, the audience almost weeps with Falstaff for the loss of such a dear friend.

The only actress to convincingly portray a man is the dynamic Zillah Glory. Her Ned Poins, a member of Hal and Falstaff’s band, and her warrior Worcester are masculine in different ways. Poins is the jovial prankster, always ready for a jest, while her Worcester is the valiant, charismatic rival Hotspur was meant to be.

Yet, it is as Lady Percy, Hotspur’s grieving widow, that Glory stops the show and drives home to theatergoers the human cost of war. Her performance is raw, riveting and utterly believable.

The true star of this production is the set, designed by Robin Vest. The map of the Britain on the floor of the thrust stage that juts out into the audience is fascinating to peruse during intermission, and informs all the action. Upstage, lit from behind, is the image of the crown. Always present, Vest’s crown appears to hover over the production even though it never actually moves. Sometimes, it seems sinister but, at other moments, its seductive power is overwhelming thanks to Brian J. Lilienthal’s thoughtful lighting design. Chelsea Kerl’s period costumes set the show solidly in the 15th century but also allow the actors to quickly changes roles.

Taintor’s “Henry IV” is a disappointment after last season’s dynamic and challenging shows, including Shakespeare’s “Julius Caesar” that somehow foreshadowed the current toxic political climate. The performances of Hurley, Klup and Glory along with Vest’s set nearly save the show but they can’t overcome their castmates’ poor performances or an overly long running time.

“Henry IV” will be performed through Sunday at the Stonington Opera House. For information, call 367-2788 or visit operahousearts.org.