Rachel Sands (Rosemary Dunsmore), a schizophrenic undergoing experimental treatment at a pharmaceutical clinic, is accused of murdering one of her doctors after going off her medication. McCall (Stepfanie Kramer) is convinced that Rachel is innocent--especially after a second murder takes place at the clinic. By episode's end, both McCall and Hunter (Fred Dryer) have discovered that the killings had nothing to do with mental illness...and everything to do with the World's Oldest Motive. ~ Hal Erickson, Rovi