Is there such a thing as a killjoy fantasy? If so, Jim Knable’s “Spain,” at the Lucille Lortel Theatre, belongs to the genre.

Like its heroine, the unbalanced Barbara (Annabella Sciorra), “Spain” likes its fantasy full-color and uncensored: a guidebook Spain of flamenco, roosters, and Picassos. Yet “Spain” also shares Barbara’s puritanical impulse to squelch and punish her fantasies. To this uneasy alliance of freedom and repression, add Mr. Knable’s obvious desire to craft a latter-day “Don Quixote” narrative, and you have the raw ingredients of “Spain,” a play whose complexities only serve to make it clamorous and unfocused.

Mr. Knable’s Quixote-in-waiting is the woebegone Barbara, recently abandoned by her husband (as we are told more than once) for “some slut with a boob job.” The 40-something Barbara, played with a frenetic but appealing quality by Ms. Sciorra, is hanging around the apartment in her hoodie when a conquistador (Michael Aronov) materializes on her couch — followed closely by an ancient Mayan priestess (Lisa Kron).

So far, so good — these are Barbara’s imaginary friends. But then Mr. Knable begins to complicate the picture. Her uptight friend from the office, Diversion (Veanne Cox), turns out to be able to see and touch the conquistador — though he has no real-life counterpart, as he would in Cervantes’s conception. When Barbara’s ex-husband John (Erik Jensen) appears, he seems real enough — until Barbara, in a burst of uncontained fury, somehow manages to stab him with the conquistador’s (imaginary?) sword.

Cue the sirens and the orange prison jumpsuit, and we seem to be back in Cervantes’s parallel universe, in which Barbara, who is “having episodes,” turns out to have stabbed her ex-husband with a kitchen knife. Or has she? Without giving too much away, I can say that the question of what’s real and what’s not real will be reopened, only to be given a resoundingly pedestrian answer.

Setting aside Mr. Knable’s haphazard handling of the distinction between fantasy and reality — which would seem a serious flaw in any update of “Don Quixote” — there is the nagging question of why Barbara is to be punished and pathologized for her fantasy life. There is something unsporting in the way “Spain” tosses a jolly conquistador into Barbara’s living room, then makes her pay dearly for the pleasure.

Perhaps Barbara has to pay because some of her fantasies are so uncouth. Besides her sheltered and uninformed ideas about Spain, she has an unsettling capacity for being stimulated by the conquistador’s stories of rape, murder, and pillage. “Tell me what it feels like to kill someone,” Barbara coos into the conquistador’s ears, leaping off the couch to gleefully reenact a raid on a village, relishing every gruesome detail.

It’s hard to say which is more offensive — the way Barbara’s bloodlust quickens when she hears the conquistador talk of slaughtering “the savages,” or the ease with which she equates the destruction of a civilization with the murder of her lousy husband. And yet these lapses might be forgivable; after all, there’s something about fantasy that is inherently against our better judgment: It’s the place where all those unspeakable thoughts and impulses burst free. The trouble with “Spain” is that it can’t decide whether to let Barbara off the hook for her bad fantasies. While the play flips back and forth on the question, the supporting characters dash in and out: Ms. Kron dons a series of disguises and accents, Ms. Cox appears in a flamenco gown and throws down a few steps, Mr. Jensen strums a few Spanish guitar chords, and Mr. Aronov has an onstage sex scene with Ms. Sciorra.

Jeremy Dobrish directs the formidable traffic gracefully, and he uses the ample jokes and gags — and the actors’ comic chops — to drive the meandering narrative to the finish line. But there’s no satisfaction waiting for this knight-errant — just a neat summation that presses Barbara’s hallucinations into the service of another master: pop psychology. Alas, in Mr. Knable’s “Spain,” fantasy is the genie that always gets put back in the bottle.

Until November 17 (121 Christopher St. at Bedford Street, 212-279-4200).