When a man is shot point blank in a casino, the CSI team is called in to investigate, and they find the culprit is a young man in a yellow polo shirt. They use sophisticated face recognition software to track him through the hotel casino via the security cameras. However, there turns out to be more than one of him. In fact, there are four. They were all born of the same egg that divided four times - and four separate embryos were inseminated into four different women over time. The man who was shot was the biological father of all the boys.