The Carter family has just settled down for dinner when an explosion shatters the peace. The Carters' next-door neighbor, a crusading investigator working with District Attorney Palmer (Frederic Tozere) to take down their city's criminally corrupt mayor and his political machine, was the victim of a car bombing. The Carters witness crooked cop Nick Bartel (John Gallaudet) leaving the scene of the crime, now placing them at the center of the D.A.'s case against the mayor. Palmer is confident that the civic-minded Carters' testimonies will help take down the mayor, but Bartel terrorizes the Carters at the direction of the ruthless mayor. After the youngest member of the Carter family is kidnapped, grandfather and Spanish-American War veteran Ulysses Porterfield (Charley Grapewin) takes matters into his own hands to save his family and District Attorney Palmer's court case.