A New Day

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 he was stuck in traffic with his new girlfriend at the time of death. However, a camera at a gas station shows otherwise for the girlfriend's alibi. She was not in the vehicle. The father is complicit, but he reveals the baby was taken to a church. Meanwhile, 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; and the team is called to a car accident that claimed the life of Detective Frost.