Briscoe and Curtis investigate the murder of Sarah Kincaid, a mathematics graduate student who was found murdered in the university library. The autopsy reveals that Sarah was strangled and also that she was 9 weeks pregnant, even though her bereaved father says she didn't have a boyfriend. Their initial inquiries are directed to a recently released ex-con but they learn that the victim had had a rather loud argument with her academic advisor, Dr. Clemente. When he is cleared however, the DNA testing of the fetus leads them to Dennis Michaels, who is engaged to Sarah's roommate. Another library patron puts them in the direction of a young preppy he saw there and it leads them to Peter Kelly, one of Dennis' good friends.
—garykmcd