Plot summary
A woman is stabbed to death while jogging in a park. The investigation is stepped up when an empty baby stroller, believed to have contained her baby, is found nearby. The baby's father, the woman's ex-husband, is questioned, but claims he was stuck in traffic with his girlfriend at the time of death. Frankie and Maura decide they are too much like family to pursue a relationship; Jane deals with morning sickness while unsuccessfully trying to hide her pregnancy from her mother. The team is called to a car accident that claimed the life of Detective Frost.
Credits
Adapted from Wikipedia contributors, List of Rizzoli & Isles episodes. HTML formatting and reference markers removed.