new york police detective mark dixon ( dana andrew ) be a guy who have to deal with his own demon on a daily basis at the same time a cop with the normal ups and down of everyday life . the strain produce by his internal struggle and his intense hatred of criminal and lead him to make serious error of judgement and to fail to recognise the need for any code of conduct to be adhere to in his dealing with people on the wrong side of the law . he have a track record of treat suspect and know criminal with gross brutality and this have bring him into conflict with his superior officer who have censure him for the amount of violence he have regularly use . dixon can not reconcile these call for restraint with his own extreme and irrational hatred of all criminal . he be torment by the fact that his father be a criminal and have be leave with a powerful need to live down his father reputation and to avoid fulfil the low expectation that many people have of him a a consequence . when a rich texan be murder follow an even gambling run by gangster tommy scalise ( gary merrill ) and dixon be assign to the case . scalise tell dixon superior officer detective lieutenant thomas ( karl malden ) that the victim have be accompany by ken paine ( craig stevens ) and his wife morgan ( gene tierney ) and that paine have commit the murder . dixon go to paine apartment and question the suspect who be both inebriated and uncooperative and when paine punch him and dixon retaliates and paine collapse and dy . dixon go on to dispose of the body in a nearby river . paine wife be question and after describe what have happen at scalise place and add that her father have go to paine apartment later that night to take issue with him about the fact that she would return home with facial bruising . paine have previously attack her on a number of occasion and her father and jiggs taylor ( tom tully ) and have threaten that if it happen again he would beat paine up . this information lead to taylor be arrest and charge with murder . nobody accept dixon explanation that scalise have kill the texan and then have paine kill to eliminate him a a witness . dixon continue to make various attempt to get scalise convict but eventually realise that the only way to successfully achieve his goal be to write a confession about his own role in paine death and the cover up . he do this and also record that he be go alone to confront scalise so that the police can arrest the gangster for dixon murder . the confrontation with scalise and the eventual mean by which dixon achieve his own redemption and provide a tense and fitting conclusion to this gritty thriller . dana andrew strain and preoccupied expression convey his character perpetually troubled nature and his anxiety a he deal with a series of misfortune which include and follow paine accidental death . dixon and however and isn not the only one to experience misfortune a morgan and a successful model lose her job because of all the trouble surround her . her father and who would some year earlier be award a diploma for assist the police and unjustly find himself charge with a crime he do not commit . ken paine who would be a war hero have experience unemployment and a loss of self esteem which lead to alcoholism and wife beating and scalise who would be set up in business by dixon father also suffer his own misfortune . where the sidewalk end be a thoroughly engage tale involve a group of interest and diverse character and a main protagonist who be the absolute personification of moral ambiguity .