"On Dangerous Ground" is for some a film noir classic, for me well it's a good 1950s thriller/ character study which is not what I call film noir but then film noir is a term which seems to cover a wide spectrum of ideas. What is nice about "On Dangerous Ground" for me is that watching now you could say that it was influential when it came to Dirty Harry especially "Sudden Impact" because the initial set up is similar. Here we have a tough cop whose dedication to getting criminals has pushed him to cross boundaries as he dishes out violent beatings leading to him being sent to deal with an out of town crime away from the heat of his latest violent outburst. What follows is different from "Sudden Impact" but no less satisfying as our tough cop gets to see things from the other side.
Det. Jim Wilson (Robert Ryan - Return of the Badmen) is dedicated to his job, as a single man he takes work home and it consumes him to the point that dealing with the filth of the city day in day out has started to turn him into a violent cop known for dishing out beatings. When his latest violent outbursts leads to a law suit he is sent to a town up north to assist in the case of a murder of a young girl and finds himself faced with a mirror image of himself in Walter Brent (Ward Bond - Only the Valiant), the father of the girl who with his shotgun is hell bent on finding his daughter's killer and getting justice. Seeing someone so angry makes Jim think especially when he meets Mary Malden (Ida Lupino), the blind sister of the young man they are hunting down and it forces Jim to change his ways as he feels something for Mary.
For me whilst "On Dangerous Ground" is a thriller as we have the second half which features a hunt for a murderer it is really more of a character study and is why personally I don't see it as a pure film-noir. But it is an entertaining character study with an atmospheric first half as the character of Jim Wilson is established quite cleverly. The opening which sees various detectives getting ready for work from those who are married or have kids to the single Jim who over breakfast is scouring police files for information on bad guys. It immediately establishes that the job has consumed him and we discover exactly how much as we watch him flip out when left alone with a suspect terrifying them as he prepares to dish out a violent beating. That scene is one of the movies most memorable because there is almost this split personality as Jim pretty much turns psycho.
So in essence the first half sets up Jim Wilson as an almost forerunner to Dirty Harry and as already pointed out "On Dangerous Ground" has similarities with "Sudden Impact" as after getting in trouble with his boss for his brutality Jim is sent out of town to assist in a case. This is where it switches things up because Jim meets angry father Walter and can see elements of himself in the enraged man with a shotgun. But then when he meets Mary he finds himself conflicted because for the first time he finds himself caring for someone and that makes him change his attitude to going after her brother and what Walter plans to do. As I said whilst we have this thriller as to what will happen if they catch Mary's brother Danny the focus is on the character of Jim and whether he changes or returns back to his job still a cop ready to beat up people.
As such whilst "On Dangerous Ground" has good performances from Ward Bond and Ida Lupino, who does a brilliant job of playing a blind woman, the focus is on Jim and therefore on Robert Ryan. And Ryan is brilliant especially during the first half delivering terror when it comes to the hotel scene and he turns into a psycho ready to beat a suspect senseless. Even in the second half Ryan is good, delivering the confusion of his conflicted feelings between doing what he has always done and suddenly finding himself caring for Mary.
What this all boils down to is that "On Dangerous Ground" is an entertaining thriller but a superior character study which for me isn't what I class as pure film noir. Its success lies firmly on the shoulders of Robert Ryan who is spectacular during the first half as he brings his bitter detective to full terrifying life.