In The Star Witness gangster chief Ralph Ince makes two big mistakes. One is that he does commit a murder. The second is that in escaping he did a brief home invasion of your average American family who are now mostly witnesses to the crime he committed. But getting them to tell their story is the subject of this film and it's what District Attorney Walter Huston has to do.
You can't get much more average than the Leeds family. Father and mother Grant Mitchell and Frances Starr, children, Sally Blane, Edward Nugent, George Ernest, and Dickie Moore. And they have their maternal grandfather Chic Sale living with them as well. He's the only one that wants to do his civic duty and hence he's Huston's Star Witness.
Sale has a really great part as the feisty old Civil War veteran and he steals every scene he's in, even from Walter Huston. He also speaks some of the more ethnocentric lines that mirror the view that The Star Witness takes about foreigners coming in to ruin this country. That was not an uncommon view of what Middle America thought of the urban gangsters who seem to come up from nowhere during those Prohibition days.
The Leeds family endures a lot, a beating to one family member and a kidnapping of another. The film earned an Oscar nomination for Best Original Screenplay. And the shootout with the gang and law enforcement is one of the best that Warner Brothers did at the time. Of course this having been directed by William Wellman who did The Public Enemy that year, you would expect the best.