Betsy Palmer & Jack Lord in "The True Story of Lynn Stuart" (1958) - Gavin MacLeod's first film

Phyllis Carter, a young mother in Orange County, volunteers to become an undercover narcotics agent after a police car chase kills two drug addicts. The police give her the identity of Lynn Stuart, an ex‑convict, and a waitress job at a diner frequented by a drug gang. She infiltrates the gang, becomes the girlfriend of suspect Willie Down, and gathers evidence that leads to the arrest of the gang's leaders. While her son is hospitalized, the gang grows suspicious of her and plans to kill her, but a police raid saves her. After testifying before a grand jury, Phyllis is reunited with her family and the gang is dismantled.