Mouthpiece finds veteran Canadian filmmaker Patricia Rozema at the top of her game. It’s an emotionally rich and stylistically assured drama that traces one young woman’s coming to terms with the death of her mother.

Based on the avant-garde play written and performed by Amy Nostbakken and Norah Sadava, the story explores two competing facets of a woman named Cassandra. This is visually exemplified by having both actors occupy the same space, forming a manifest exemplar for the conflicted feelings that are literally splitting her apart. Nostbakken and Sadava have an obvious intimacy with the character they both developed and performed on stage, which makes their mirrored performances both precise and extremely effective.

The film has little trace of the confines of an overtly theatrical exercise. Despite having a relatively sparse setting, Rozema manages to inject some real cinematic scope to the project, allowing camerawork, montage and the like that transcend anything that can be accomplished within the constraints of a proscenium. This seems faint praise, but far too often the translation from stage to screen results in a stultified, almost passive type of filmmaking. Thanks to her vision and her collaborators, Rozema manages to inject quite a bit of intimacy and intensity into the telling of this story.

As Cassandra comes to terms with her own grief, the film settles into a less jarring rhythm, proving a further echo to her state of mind that’s shared by the synchronized performance. It’s a heightened yet clever way of making overt the dichotomy of Cassandra’s own feelings. As the baton is passed back and forth between the two performers, the divisions begin to soften, becoming far less a yin/yang, id/ego divide and settling into something far more complex.

Mouthpiece is bold, experimental and highly provocative, but done with enough craft and energy that it becomes highly engaging. The peak of Rozema’s storied career, her teaming with Nostbakken and Sadava makes for a fine synergy between the theatrical and the cinematic, resulting in an exceptional film.