The Secret Life Of Words captures the imagination with its title from act one. Some sort of emergency. The voice of someone drowned out. Later the world of sound as experienced through a young factory worker. And again as she switches her hearing aid on.

But this powerful melodrama highlights much deeper human rights issues. Things that can hardly be spoken. We follow the secretive, insular Hanna (Sarah Polley) as she is forced to take a holiday – only to get work on an oil rig. The part could almost have been written for a young Jodie Foster. Hanna gives nothing away about herself, and is a model worker. Yet we are convinced that her reticence is due to some traumatic experience she cannot divulge.

Josef (Tim Robbins) is bedridden on the rig. He tries to wheedle information out of Hanna about herself. Yet he too harbours a secret he is ashamed to tell anyone.

Their cathartic emotional journey towards one another is compelling and realistic enough to forgive the clichés in this somewhat stagey story. Everything hinges on their acting and they are both up to the challenge. Robbins is in his element, having found a film that tackles important moral outrages without being patronising. Polley is a revelation unfolding before our eyes. When she eventually puts her life story into words, it is more than most of the audience can bear.

When Hanna and Josef connect, their words have been pared down. Hinting at the inexpressible. Yet the past still haunts them. Only when the things given life again by their words have died, can they rise above the waves that have engulfed them.

Hanna says: "I may begin to cry and cry so very much that nothing or nobody can stop me and the tears will fill the room and I won't be able to breath and I will pull you down with me and we'll both drown." To which Josef replies: "I'll learn how to swim, Hanna. I swear, I'll learn how to swim."

The weakness of a Secret Life of Words is that the minimalist style could be too slow for many viewers. Unashamedly low budget, it focuses on good acting in claustrophobically tight sets. "There are very few things..," a voice-over says at the start of the film, "...silence and words.¨

Indeed, there is very little else in the movie. The sound contrasts bring us back to the silence and words of the two leads. We stitch off from the coarse, macho joshing of the male crew. The oceanographer measuring the number of waves hitting the rig is cute, but his concern over what is really important will probably not be heard by anyone else. Hanna's fragility, and that she is so much more than a factory worker, is what intrigues us. This bleak and beautiful film is a triumph of dialogue.

Hopefully audiences will stop to listen.