Matilda Ridgway (Catherine) and Adriano Cappelletta (Hal) in David Auburn's  Pulitzer Prize winning PROOF at the Ensemble Theatre
How many levels of proof are required?!- Matilda Ridgway (Catherine) and Adriano Cappelletta (Hal) in David Auburn’s engrossing play, PROOF. Pic Clare Hawley

David Auburn’s PROOF takes us into a young woman’s world as she reaches a significant milestone in her life, turning a quarter of a century. Joining Catherine (Matilda Ridgway) in her birthday celebrations is her estranged stocks analyst sister, Claire (Catherine McGraffin), who travels from New York, Catherine is based in Chicago, and a new beau, Hal (Adriano Cappelletta). Absent is her irascible, brilliant Mathematic professor father, Robert (Michael Ross), who recently passed away after a long battle with mental illness.

Catherine’s life is delicately balanced. She appears to have inherited both her father’s sharp intelligence and his dark moods. The heat is turned on Catherine when her older sister unveils her plan to sell the family home and take Catherine back to live with her in New York and to see a treating psychiatrist. Not quite what was in Catherine’s plans…with the new found freedom that she has with her father’s passing, and with a budding love interest in Hal, a former PhD student of her father’s, who has been hanging around the family home, trying to decipher Robert’s old notebooks.

Auburn keeps us guessing until the very last scene as to whether Catherine’s future will be bright or dark.

After seeing her performance in the leading role, no further proof is needed that Matilda Ridgway, herself an Ensemble Studios graduate, is one of the rising young talents on the Sydney theatre scene. She clearly portrays her character’s angst a long with a healthy, strong will.

Plenty of sparks fly in the scenes between Ridgway and another fine young actress in Catherine McGraffin as her pushy older sister.

There’s a wonderfully poignant scene played out between Ridgway and veteran Ensemble performer Michael Ross as her ailing father, depicting the profound extent of Robert’s illness.

Adriano Cappelletta displayed a light, warm, touch as Catherine’s sympathetic suitor.

Auburn weaves through his play an intriguing parallel between the requirement for proof in mathematical formulas and the need for trust, validation and certainty in relationships.

With the play’s intricate plotting, clear direction by Sandra Bates, strong performances by the cast, yet another impressive set by Graham Maclean, and Trudy Dalgleish’s elegantly lit stage, PROOF adds up to an engaging and rewarding night at the theatre.

David Auburn’s PROOF opened at the Ensemble Theatre, 78 McDougall Street, Kirribilli on Wednesday 5th February and is playing until Saturday 8th March, 2014. Running time is 2 hours and 20 minutes including one interval.