"Harry Caul is a nationally known expert on surveillance. The Director of a large company has hired him to record the conversations of two of the Director's employees. Some years previous, Harry's work directly led to the murder of three people, and now he has reason to fear that it will happen again."

What I like about this movie:
The question of what the conversation he recorded is really about definitely leaves you in anticipation until the end. A very subtle movie. Slow moving at times but worth the wait. It plays with your emotions at the end by making you do a complete 180 on what you thought was happening.