First, you must pay attention during this movie for every frame of the movie. You cannot understand part of the movie without understanding all of the movie. Unlike many movies in which dream sequences play a major part, this movie is all about the dream and part of the complexity is sorting out the dream world from reality. In fact, that sorting out is the job both of the audience and of the cast of actors as the essence of the story is being able to tell the dream from the reality.

In this dream world, it is possible for sophisticated espionage agents and dream agents to steal information for corporate espionage or other reasons by entering a persons dreams and extracting information from the dream. Leonardo DiCaprio plays Dom Cobb an expert in the field. In the early stages of the movie he appears to fail at a planned extraction only to find that the job was in fact an audition for someone capable of the ultimate dream world espionage of planting an idea into someone's subconscious in a dream rather than just extracting information. For the plot to work, the victim must believe that the idea is his own so that he will act on it and change his behavior and possibly his very life.

The story line is very complicated and involves entering and creating various levels of dream worlds so that they are dreaming within dreams and then dreaming within that dream so that there are multiple layers of dreams with each one acting to stretch out time so that 10 seconds in dream layer one is maybe 60 minutes in dream layer two, which may be two weeks in dream layer three and 10 years in dream layer 4.

The acting, especially by Leonardo DiCaprio as Cobb and by Ellen Page as Ariadne makes the story line much more believable. The emotional baggage that Cobb brings with him adds to the complexity of the story line and to the emotional impact of the movie. The action sequences that take place within the dream layers are no less believable for being incredible since we have already accepted that this is a dream world.

I recommend this movie as one of those rare movies that makes extensive use of high tech special effects and incredible action scenes but at the same time relies on and stays true to the story line of the movie so that when you walk out of the theater you are thinking about the characters and the story line and not just the action sequences. 

Excellent entertainment.