Based on the novel of the same name by Philip K. Dick, A Scanner Darkly tells the story of a near-future dystopia in which America has virtually lost the war on drugs. Robert Arctor (Keanu Reeves), a narcotics cop in Orange County, California, is undercover so deep that he has become an addict. He is wooing Donna (Winona Ryder), a dealer, to ferret out her supplier. At the same time, he receives orders to spy on his housemates (Robert Downey Jr., Woody Harrelson, Rory Cochrane), one of whom is suspected of being Donna's biggest customer.