Because this film starred Dennis O'Keefe (who was wonderful in his Film Noir appearances), I was sure to see it. And fortunately, the overall effort was exciting and engaging--making it a decent later example of the genre. While not as bloody and earthy as many Noir films, due to the head of the mob priding himself on being a well-spoken gentleman, nevertheless is a decent film of this type.
The film begins with a contract killing so stop an accountant from spilling his guts about organized crime. A citizen's group decides that they need to try a new way to infiltrate the mob--send in a freelance agent who isn't a cop or part of the Treasury or Justice Departments. So Dennis O'Keefe is recruited and he is able to eventually rise very high in the ranks--and leading to a wonderful showdown.
I think the reason I like O'Keefe in these films is because he's so ugly--or at best ordinary looking. For Noir, this is great, as pretty boys and the like are NOT something you'd expect. So, when Edmund O'Brien isn't available, O'Keefe is a good substitute.
Full of excellent intrigue, an interesting and unusual plot and sure to please fans of the genre, CHICAGO SYNDICATE nearly earns an 8--it's that good.
FYI--It is interesting that in one scene where they are standing outside a movie theater, the picture listed on the marquee is ON THE WATERFRONT--another film about mobsters which came out at about the same time as CHICAGO SYNDICATE.