NEW YORK — The teenager crouches on the rectory’s kitchen floor, idly inking his forearm with a ballpoint pen. His face is bruised, his complexion pale green, his hair dusted with white. He’s a ghost, and a persistent one, trailing his older brother, Nathan, through life.

That’s hardly the only haunting going on in Sara Fellini’s unwieldy new play, “In Vestments,” in which Isaac Byrne’s high-energy production is by turns earnest and campy, wrenching and visually eloquent. Set in a Roman Catholic parish called Our Lady of Perpetual Sighs, it’s performed in the intimate chapel of West Park Presbyterian Church on the Upper West Side, where the audience sits in pews lining the walls.

As the play begins, the priests face a quandary: What to do with sacramental wine that was tainted by plaster falling from the ceiling at the moment of transubstantiation, just as the wine became the blood of Christ?

The metaphor — poison in the very structure of the Church — is worryingly on the nose, and the money-grubbing ways of Father Falke (Ted Wold), the ranking priest, similarly lack subtlety. But the play mostly gets better from there, even if it refuses to settle into a tone.

Presented by Theater 4the People, with free admission, “In Vestments” is a sort of dramaturgical jambalaya, flavored with the full-throated music of Jacques Brel, sung by Pierre Marais. It borrows from “The Rocky Horror Picture Show,” too, which is fitting: Almost everyone here is doing a kind of time warp, the past impinging on the present.

Nathan (Adam Belvo), a drug-addicted priest with red-rimmed eyes, is stalked by guilt over the death of his brother, Jack (Peter Oliver). Yves (Samuel Adams), a visiting priest with a slippery accent, is fleeing the memory of abuse.

Maeve (Fellini), Nathan’s sister, who cooks for the men, has her own reasons for clinging to the Church, though she resents its silencing of women’s voices. Three nuns in full habit occasionally appear, never uttering a word, their faces completely covered in white.

And then there’s a bearded guy named Joshua (Eric Soto). Bare-chested in a crown of thorns, he hangs out unseen in the kitchen, affably clutching a mug of coffee in hands with puncture wounds. It’s a comical image, but there’s force behind it. He would love to help these people, if only they’d realize he was there.

“In Vestments” continues through May 30 at West Park Presbyterian Church, 165 West 86th St., Manhattan.