The structure is unconventional. Basically the first two hours play out as the dream of a very troubled young woman by the name of Diane Selwyn. In the final 30 minutes we are taken into Diane's reality. Mullholland Drive is a very disturbing portrait of the inner world of a woman about to commit suicide and we learn about her life and what led her to murder and suicide through the dream imagery of the first two hours.
I didn´t know Naomi Watts, she´s great. Her performance is believable despite whatever character she´s playing or situation she´s in.