Roslyn Chambers can be found at the Compound where she has her base of operations and uses torture to extract data from abducted people while trying to create a test to detect synths. After the testing, the abductees are killed. Her ultimate goal is to use her test to destroy all synths in the Commonwealth. She bears a deep hatred towards synths and the Institute ever since her parents were killed in front of her as a child during the 'Broken Mask' incident, described in The Synthetic Truth.
In the quest Human Error, Dr. Chambers will have imprisoned Amelia Stockton in the Compound. She will explain her motives and the history of the Compound and the Covenant to the Sole Survivor, and ask them to side with her. If her offer is refused, she will become hostile, along with everyone else in the Compound.