Bat Masterson (1958)

S2E1 To the Manner Born

An old acquaintance reaches out to Bat, requesting his help in San Francisco to investigate her daughter's fiancé, who happens to be a relative. During his inquiry, Bat discovers that the woman is a regular at a casino, where she consistently comes out ahead while her fiancé appears to be on a losing streak—one that ultimately leads to his demise.