Avner is a chief engineer in a big mining project in the north of Israel. He is happily married and has 2 beautiful children. He has a good life. One day he receives a traffic report by mail. Inside, there's a black and white photo of his wife driving her car, and next to her there's a man, holding his arm around her shoulder in a very intimate way.
And this man is NOT himself. Avner, being the man he is, doesn't go and talk to his wife (like most people would do), but instead he buys a recording device and starts to record her phone conversations. He must know who it is, and for how long, and where - he needs to know all the facts.
But before he has a chance to get them, his wife dies in a car accident and all he is left with are those unanswered questions. That, and her voice as recorded on the device.
He believes the lover has the answers, so he goes into an obsessive investigation, listening to the conversations again and again and again, trying to gather clues that will lead him to that man. As he sinks deeper and deeper into his obsession, he becomes more and more isolated from his friends, from his children.
Everything around him starts to fall apart. But while searching for one thing, he discovers another: his wife. She sounds almost like a stranger to him, even her voice feels different. He realizes that he didn't really know her. That there were parts in her personality that he couldn't, or wouldn't see before.
Gradually, the focus of his search shifts from "who is that man?" to "who was that woman?". Eventually, the search becomes a reflection of himself and his own relationship with his wife.