Shakespeare’s “The Scottish Play,” or “Scottish Tragedy,” has weathered samurai (“Throne of Blood”), mobster (“Men of Respect”) and Pennsylvania fast food feud (“Scotland, Pa.”) adaptations.

So why not a “Curse of Macbeth” farce?

“Ghost Light” gets by on theater milieu and stage superstitions, with the odd biting line or funny turn from a cast that includes Cary Elwes, Carol Kane and Shannyn Sossaman, taking its not-that-good sweet time building up a head of steam.

But the third act, the actual staged disaster of particularly cursed production of “Macbeth” (“cur-sed,” as the Bard purists put it) delivers on much of the promise the premise lays out. Before that, call it a half-blood farce, a step slow with players half as antic as they need to be to pull it off.

A bus tour of Shakespeareans roll up to the weathered River Lodge in the Massachusetts Berkshires, “closed for the season” (fall), but with a new owner anxious to re-open the gem of an old barn converted into a theater.

The troupe is to do “The Scottish Play,” and the grizzled veterans of the tour (Carol Kane, Steve Tom and Roger Bart, as Henry the director) have to explain to the less experienced the “Curse” of saying “Macbeth” aloud, the remedies for relieving the curse should some careless or in this case, enraged enough to commit sabotage, utter the cursed Thane’s name.

Who could be that resentful? Maybe the veteran who toured Britain as First Witch, now reduced to third (Kane), the inept, hard-of-hearing soap star leading man (Elwes), his embittered wife and co-star Lady Macbeth (Sossaman), or the arrogant British understudy sleeping with Lady Macbeth on the sly and coveting the lead role (Tom Riley)?

Kane and Tom play the actors most-steeped in theater-lore — “Young man, you shouldn’t EVER whistle in the theater!” They even explain the tradition of the “Ghost light,” which is what you see on an empty stage between rehearsals and performances.

Bart (“The Producers”) and Scott Adsit (“30 Rock”), as stage manager Archie play along, and even demonstrate what is required to allay the curse once somebody invokes it. Funny.

Considering the on-again/off-again gay couple (Sheldon Best and Alex Protenko), the ingenue (Caroline Portu) cavorting with the props man, the Appalachian Trail backpacker (Danielle Campbell of TV’s “The Originals”) pressed into service as another witch, it’s a wonder anybody has time.

But sure enough, the word is spoken, the curse not-reversed and all heck breaks loose. Or should, is a more spritely production.

Thomas (Riley) and Liz (Sossaman) have ghostly, blood-stained visions, Juliet (Campbell) starts taking the “witch” thing a little too seriously, accidents happen and hallucinations spread far and wide.

The last to notice is probably Alex (Elwes), the soap star with hearing problems cast in the title role.

“Let me sit up and gather my thoughts.”

“That should be QUITE a harvest!”

As Liz/Lady Macbeth finds herself scrubbing and scrubbing to get that “dam-ned spot” of blood off her hands — “Look at my hands!” “They’re LOVELY hands…They don’t show your age at all!” — and invoking a taunt Lady Macbeth would have KILLED to have thought up — “Man up!” — we start to fear for the players and not just the potentially disastrous night of theater they’re about to mount.

Losing control when “the witches’ curse is unleashed” they find themselves forced to act out the murderous machinations Shakespeare cooked up 400+ years ago.

“You know how the play goes. We murder the king!”

Co-writer/director John Stimpson is hard-pressed to put enough that’s amusing up here to sustain the film’s meager forward momentum until that third act.

We should get a more “Noises Off” riff on the star who can’t recall the most famous phrases in Shakespeare — “Tomorrow and…LINE?” Dozens more moments like that were called for.

Theater fans will bask in the knowing glow of “theater types” and offstage ensemble shenanigans. If only there were more of them for everybody to giggle at and feel invited to the party.

Because curse or no curse, “Ghost Light” is never more than a “brief candle.” If not “a tale told by an idiot,” it still lacks the “sound and fury” to ever rise above what one suspects will be its final, deserving destination — Netflix.

Tomorrow and…Line?

Danielle Campbell hiker

a method taught to me by Lord Laurence Olivier’s stunt double..

Nigel gay

You want it to be convincing, right?

A little more butch would be good

Everyone believes that.

Everyone KNOWS that!

married Lady Macbeth fooling around with the understudy

The “ghost light” is another of those theater traditions,

old farts explaining theater traditions to the newbies

You how the play goes. We murder the king.

burning on an empty stage

an older leading man without talent or a clue

tiny but very cute little converted barn theater

some lamenting their lot

resentful British understudy

Bart, producer?

MPAA Rating: unrated

Cast: Cary Elwes, Danielle Campbell, Shannyn Sossamon, Carol Kane, Roger Bart, Tom Riley

Credits:Directed by John Stimpson, script by John Stimpson, Geoffrey Taylor . An H9 release.

Running time: 1:42