Compelling theater isn’t always easy to watch. Sometimes it is horrifying.

Watching Kathyrn Jurbala wander the stage — her fingers contorted like claws, her nose elevated like a blind zombie sniffing the air for the scent of prey — brings a compelling sense of the horrific to her portrayal of Helen Keller in The Actors Group production of "The Miracle Worker."

On one level we know there was a tremendous intellect trapped in Keller’s cruelly disabled body. But Jurbala’s performance takes us beyond what we know of Helen Keller and into the horrifying situation of being in close proximity to someone who is physically human but with whom it is impossible to communicate beyond the level of communicating with a dog or monkey.

There is also a deeper horror to be found in Jurbala’s performance. Imagine what it must have been like for Helen to grow from infancy being blind and deaf and able to communicate only on the most basic level, yet aware those around her possessed capabilities she lacked.

Yes, TAG is again offering provocative and thought-provoking theater.

Jurbala’s performance as a spoiled, cunning and almost feral child is the foundation of the production. The story is so well known there are no surprises, but director Laurie Tano­ura still succeeds in making key moments suspenseful.

Hoku Gilbert (Annie Sullivan) plays the titular "miracle worker" quite nicely. Sullivan brought emotional baggage of her own to the job of attempting to teach a deaf, blind and uncontrollable girl. Gerald Alt­wies (Captain Keller), Lea Gru­pen (Kate Keller) and Scott Francis Russell (James Keller) round out the core cast in the roles of Helen’s well-meaning parents and her cynical half brother.

Tanoura has chosen to make some changes in playwright William Gibson’s story and more fully develop the characters of the Kellers’ black cook and her children. The additional dialogue takes place in a vacuum and adds no insights to Gibson’s story about Sullivan’s struggle to reach her unwilling student, or Sullivan’s struggle to convince Helen’s well-intentioned parents that a relentless tough-love approach is the best way to do it.

Several scenes with disco lights and cacophonous offstage voices create the impression that Sullivan is having flashbacks to her own early years as an institutionalized semiblind child. Tano­ura would have done well to include a bit of Sullivan’s back story in her director’s notes. As it is, the disco light scenes seem as detached from the prog­ress of the story as the servants’ added dialogue.