IMPACT is marketed as "film noir," but about the only element of that genre it has in pure form is a treacherous wife and her vile lover. Otherwise it's an engaging crime drama with so many juicy plot twists and surprises that it's impossible to talk about the plot without including spoilers.
The straightforward direction is by Arthur Lubin, who would release the first of five Francis the Talking Mule movies the year IMPACT was released. Mr. Lubin also developed the Mr. Ed television series, as well as directing Maverick and Bonanza. This is a piece with those other works; not a lot of style but uniformly entertaining.
Brian Donlevy is excellent as the wronged husband. In a scene that was probably more shocking in 1949 than it is today, Donlevy sobs uncontrollably. Oddly enough the two women in the movie - Good Girl Ella Raines and Bad Girl/Scheming Wife Helen Walker let drop nary a sincere tear. Walker's character does indeed put on a show of tears for the suspicious detective, played with a slight Irish brogue by the always reliable Charles Coburn.
If you're expecting cartons of cigarettes and a city full of shadowed streets you're going to be disappointed. There's more than a touch of evil in this one, but it's not the focal point. If you want a good story competently told, this is for you. IMPACT is a lot of fun.