Harry Caul (Gene Hackman) is a hired surveillance expert who specialises in spying on people using a combination of his own equipment and the latest in technology. During his personal life he is a recluse, living a life in solitude and even only rarely visiting the woman he loves for fear of commitment.
After being hired to discretely record a conversation between a young couple he becomes aware that his employer may be plotting to murder them. Having already had a similar experience in the past he must decipher the recording to try and understand the motives behind his employment or forever live with the consequences - again.
But Harry Caul is a very complex character. He begins the film as a man who religiously refuses to listen to the content of his espionage - preferring to just get a clear sound. Gradually details about his past and present become clearer as the viewer becomes acutely aware that Caul would like nothing better than be left alone - except perhaps to know that he is the best in his field of expertise.
The conversation itself is delivered in a manner than keeps the viewer on edge. Starting with the actual event of the recording the viewer meets the couple whose speech becomes integral with the film's storyline. Then, playback after playback a back-story is formed which enables Caul to confront his employer - but one should always remember that only so much evidence can be gained from a single event.
Hackman is simply outstanding as Caul, portraying every single corner of the multi-dimensional character perfectly. Around Hackman there are a number of other supporting actors but Hackman makes the film his, rightly pushing the others to the back of the class.
A brilliant character study, an enticing drama and an intelligent mystery.