Just because someone's a sadist doesn't mean that someone's a bad person. This is what Gloria Grahame's character Laurel feels when she falls for Humphrey Bogart's Dixon Steele in 1950's In a Lonely Place. It's a fascinating film noir with brave performances.
Before playing the hero in movies like Casablanca and Key Largo, Bogart had a career at Warner Brothers in the 1930s playing villains opposite James Cagney and Edward G. Robinson. At the end of the 1940s, maybe Bogart was tired of being the nice guy as his role in this film and the contemporaneous The Treasure of Sierra Madre hearken back to his 30s heavies. Though he's certainly nothing as simplistic as a villain in In a Lonely Place.
He's a screenwriter tasked with adapting a book he knows is lousy so he talks a young woman at a club into coming home with him to tell him about the book so he doesn't have to read it. When she turns up murdered the next day, he doesn't seem to care much that the police think he did it. He makes morbid jokes at the police station and aside from muttering "poor kid" when he's going over crime scene photos can't seem to work up any feelings beyond a ragged bemusement.
But as luck would have it, there is a witness who can place Dixon alone at home at the time of the murder, and that's his neighbour, Laurel, who has a habit of watching him because, as she tells the police inspector, she likes his face.
Pretty soon, the two are in a relationship and it seems to go fine. Laurel, like Steele's old friends in the movie business, loves him despite the pleasure he takes in fantasising about violent acts and his tendency to lose control when his ego is bruised. Most of the time, he keeps himself under control. But unfortunately, sometimes he goes overboard when he has an excuse, as when he almost beats to death a motorist in an argument about a near accident--Laurel just barely manages to stop Dixon from smashing the guy's head with a rock.
This leaves Laurel in a tough spot. At first it's only her friends she has to argue with about the relationship but eventually she has to face the possibility that her lover, even though he's never hit her, could one day lose his cool and kill her. And considering how unreasonable he gets when his pride is hurt, the most dangerous thing in the world might be trying to leave him.
This might rank with On Dangerous Ground as my favourite Nicolas Ray film, and they're both films about violent, volatile men who are nonetheless the protagonists. Here Bogart is excellent in conveying the vulnerability of someone who really seems to care about other people but there's just something in his brain that enjoys causing pain, too. He can manage his compulsion but inevitably, as the title suggests, it isolates him.