It’s the most famous spell in literature. “Double, double, toil and trouble, fire burn, and cauldron bubble,” the three witches chant in “Macbeth,” before one announces: “By the pricking of my thumbs, something wicked this way comes.”

Enter Macbeth, with murder in his mind and violence in his heart.

But is his desire to kill the result of a fate over which he has no control? Or is it the product of his own lust and that of his wife, Lady Macbeth, who stiffens his spine when he shows doubts about getting his hands bloody?

Those two glosses have predominated in productions of the Shakespearean tragedy over the years. Director Jef Hall-Flavin marries both in an adaptation that opened Friday at Park Square Theatre.

You might call this a drive-through “Macbeth.” Already one of Shakespeare’s shortest plays, Hall-Flavin’s condensed version — aimed at high school audiences — takes just 90 minutes (not including intermission), with nine actors playing 24 characters.

While it has worthy elements, this “Macbeth” is muddled and wanting. We do get most of the great lines (“fair is foul, and foul is fair,” “screw your courage to the sticking place, and we’ll not fail”). But many are delivered like monologues at an audition, without sufficient context to convey the full richness of their meaning.

We can’t wholly blame the actors for their uncertainty at times. There’s little in this staging to indicate where the action is occurring or which character is speaking. Joseph Stanley’s set is sparse, although a cracked mirror is used effectively for some magic. The play’s warring parties are color-coordinated in some cool costumes designed by Sarah Bahr.

Still, the cast is uneven. Michael Ooms imprints the title character with his own towering physicality, but Macbeth’s emotions and intellect are not always manifest.

Vanessa Wasche’s Lady Macbeth offers far more truth onstage. The character is a craven, clawing powerhouse who knows what she wants and is willing to do whatever it takes.

Actor Eric “Pogi” Sumangil gives Banquo an eeriness, especially as an apparition smiling while Macbeth, wracked by guilt, is shown up in front of his guests. And Laura Esping acquits herself well in a variety of roles, including Lady Macduff, a mother who, with her baby, falls tremulously under Macbeth’s rage.

There have been great productions of “Macbeth” over the years, including Orson Welles’ “Voodoo Macbeth” and Max Stafford-Clark’s indelible promenade production that toured to the Guthrie Lab in 2005. Hall-Flavin has less ambitious goals — and occasionally meets them.