Please note that I saw this during previews so this is not officially a review ...
Whilst this short play has some dated elements (I do actually remember the issue of shared party lines) the emotions play in an honest and modern way and speak to the agony of a one-sided break up. Ruth Wilson plays a lonely woman, who has been dumped by her long term boyfriend who is about to get married to another woman. She has been promised a phone call and that, essentially, is the whole play. A one-woman show, we only see Ruth and we only hear her side of the phone conversations. Everything we know about "the man" comes from her reactions to his calls and to what she hears and yet we feel fully involved in the whole world that she creates.
The design is brave and effective - a vast picture window across the whole stage acts as a letterbox through which we see Ruth. Curiously, the picture window actually has glass in it so we are separated from Ruth physically except when she opens the window. The feeling is of being high up in a tall building watching someone in the adjacent building through their window but able to hear what they say. Curious but very effective at providing an intimacy and a separation to the action - we are voyeurs so a tragedy.
Ruth Wilson's performance is magnificent - she gives us everything from simpering teen love to wild outbursts of anger and periods of incredible stillness and silence. Versatile, fluid and credible. I loved it.