The fact of the matter is that there is a murder stoyline, but not much suspense there. It is an excuse to make Ethan Hawke's Vincent character sweat bullets. He shouldn't be working where he's working or doing what he's doing. The police know that he's out of place, and assume that he's the killer.
The main storyline is about how Vincent needs to use a wide array of deception in order to convince people that he is Jerome Morrow, genetically engineered superior creation, instead of himself, naturally created average citizen with heart defect. Since this is a society in which DNA testing is as common as dusting for fingerprints, the status of people with lousy genetics is pretty much determined at birth. The only way to overcome the accidents of birth is to disguise yourself through elaborate uses of someone else's blood, skin, and urine. That still doesn't guarentee that your own eyelash won't fall off, condemning you as a genetic imposter.
I was prepared to hate this movie. Movies about the fad-of-the-year,ie. genetic engineering and DNA testing this time, tend to be lousy stories banking on viewer interest to prop up a cornball plot and stereotypical characters. This movie isn't that way; primarily due to the relationship between Vincent and Jerome. Jerome is supposedly perfect, yet is confined to a wheelchair from a suicide attempt. Vincent is his eyes and ears to the world, desiring everything that Jerome forsakes. The movie could have just been about these two and it would have fine. The fact that their interaction is sacrificed for the less intriguing love story with Uma Thurman and the utterly lifeless murder plotline is unfortunate; but not fatal.
What is surprising about this movie is that failing to be the advertised neo noir picture it takes on a very spiritual attribute. Ultimately this is a movie about limitations and expectations. Although told in science fiction terminology, it's themes are as old as the book of Genesis. What people expect of you and what you expect of yourself may be important but ultimately you are capable of so much more. It's not original, it's not particularly insightful, but it is a truth to which everyone must be reminded now and then.