Harry Clarke (the persona and the person) was born out of the dysfunctional matrix of paternal abuse and maternal collusion that plagued Philip Brugglestein from his childhood through his adulthood. David Cale’s play “Harry Clarke,” currently playing at the Vineyard Theatre, is a complex and engaging psychological study of dissociative identity disorder (DID) and explores the provenance of that condition from the point of view of a man (Billy Crudup) who fled one identity and was pursued by a second that alternately brought him both pleasure and pain.

Mr. Cale’s script is carefully developed: it has a well-defined dramatic arc and it features interesting and well-developed characters with engaging and believable conflicts that drive a plot rich in twists and turns that holds the audience’s interest for the entire eighty minutes when performed. Under Leigh Silverman’s astute and unobtrusive direction, Billy Crudup engages in a dramatic battle with the script and comes up the clear victor, unearthing Mr. Cale’s treasures and bringing Harry Clarke to life with inexorable energy and irrepressible wit. Alexander Dodge’s sparse set and Alan C. Edwards’s judicious lighting contribute to the success of the performance.

Billy Crudup plays twelve characters (or more) in addition to Philip Brugglestein and his cockney Doppelganger Harry Clarke, including his abusive parents and the police officer who awakened Philip to tell him of his father’s death. After Philip’s father’s death, he moves to New York City where he and Harry impose themselves upon Mark Schmidt. Mr. Crudup portrays – rather creates – Mark, Mark’s father and his Mother Ruth, Mark’s sister Stephanie, Luke (whom he meets in a bar) from Camden, and attorneys Brad Gould and Ryan.

Mr. Crudup gives each of these dynamic characters unique personalities, facial gestures, and body movements. He accomplishes this remarkable, near impossible, task with the ease of turning a page in a script and the skill of one of the stage’s most accomplished actors. One can see Crudup’s characters not only in the traditional ways outlined earlier; one can also see the actor imagining these characters “in his head.” He even sings Stephanie’s song “Wide Back Boy” with seductive charm.

Philip and Harry (one needs to mention both personas) make it to England. How and why are the resolution of the play and it would require a spoiler’s alert to provide more details. The journey from Indiana to England provides ample opportunity for Harry to regain control over Philip and place him in challenging – albeit fascinating – situations. Each requires Philip to grapple with his personality, his superego, and his tolerance of taking risks that might result in Philip losing complete control to Harry.

David Cale’s expansive character study of the young Philip Brugglestein from South Bend, Indiana and his “alter ego” Harry Clarke raises the rich and enduring question, “Are there limits to what one does to escape verbal, psychological, and – perhaps – sexual abuse to preserve one’s life?” Additionally, is one always in control of the circumstances surrounding the techniques of survival? Finally, “Harry Clarke” successfully questions all assumptions about individual identity, ego strength, and personality that leave the audience members wondering just how much they know about themselves and their choices.