“What is the Cause of Thunder?” is a poor play done well.

The story revolves around an actress who has performed in a soap opera for 27 years and is about to be killed off. Above are Lucille Petty, left, and Susan Arnold.

We hate to say this, but:

Even a stellar cast can not redeem “What is the Cause of Thunder?,” the current offering from Beowulf Alley Theatre.

It’s a one-joke play that might be a fun 10-minute skit. But 90 minutes of a passionately narcissistic soap opera star who confuses her TV life with her home life is, frankly, supremely grating.

Noah Haidle penned this script, and the playwright does some wonderfully quirky work. “What is the Cause of Thunder?,” which has no destination and an invisible purpose, is not one of them.

So it is especially surprising the two actors in the play, Susan Arnold and Lucille Petty, embraced it and performed it with such conviction and grace.

Arnold is Ada, who has devoted 27 years of her life to performing in a soap opera. Ada is about to be killed off in the story, and the news devastates her. And why shouldn’t it? She has spent her days with murderers, pedophiles, and a set of one-good-one-bad twins for so long that the prospect of sitting at home without the drama is not a pleasant one for her. Arnold revels in the over-the-topness of the character; you just know she’s having a blast as a daytime diva. She hits all the right notes, even while the play doesn’t.

Petty takes on a slew of roles — Ophelia, Ada’s daughter in her non-TV life, as well as her twins in the soap; a nun, a dead son — basically, everyone else in the soap. Petty nails this role as she smoothly transitions from one character to the next. Her comedic timing is pristine.

Leslie J. Miller does just fine with the direction, though the time between scenes could have been more compact.

“What is the Cause of Thunder?” isn’t stellar theater. But it’s got some stellar acting and it’s local theater. Two out of three ain’t bad.

Contact reporter Kathleen Allen at kallen@azstarnet.com or 573-4128.