Martin is left on his own to solve the disappearance of Arianna Murphy, a victim's advocate from the scene of a double homicide, when Agent Medina diverts the rest of the team to investigate the abduction of a little girl from a mall.

The squad discovers a shocking truth during an investigation of Chris Howe, a missing paraplegic recently injured in a car accident. The team also continues to adjust to normal with Jack back as the head of the department.