The body of a young woman was found in the locker room of the factory where Donita works.
Police say the woman was stabbed.
The only clues are some strands of hair clutched in the hand of the victim. The hair is not hers, so police think it belongs to the murderer. According to the factory guards, no outsiders were in the building at the time of the murder. For that reason, police believe the killer is one of the 500 women who work there. To find out, the police decide to do a mass DNA screening.