A young woman disappears after her boyfriend is killed in a police shooting. Sam learns she is pregnant after a one-night stand.

When a serial killer eludes capture in Nevada and escapes with his son to New York, Jack and the team pick up the trail with the help of CSI Las Vegas team leader Gil Grissom (William Petersen).

This episode concludes a crossover with CSI: Crime Scene Investigation that begins on "Who and What".