The True Story of Lynn Stuart (1958)

Columbia goes to a series of newspaper articles about the drug traffic in this story about upper middle class housewife Betsey Palmer volunteering to go undercover for the narcotics squad. The sincerity of the story telling and, indeed, Miss Palmer's acting, manage to overcome a few holes in logic, like her ability to impersonate an ex-con after studying a list of junkie slang.

Basically the understated night-life photography of Burnett Guffey and a large cast of skilled if little-known screen actors of all ages -- including Snub Pollard and Eddie Le Veque as well as Jack Lord as the lead drug dealer -- manage to keep this interesting enough to overcome the problem. Plus Miss Palmer is gorgeous. It's a pity she didn't get a chance to be in more movies until a quarter century later, but she had plenty of work in TV.