VIDEO REWIND

Akira Kurosawa knows a good symbol when he finds one. In the opening credits of his masterful “Stray Dog,” a lone mutt pants into the camera. Later, a key character tells the detective-hero that “a stray dog becomes a mad dog.”

All this canine-consciousness pretty much sums up the protagonist, Murakami (a lean, young Toshiro Mifune). As a cop in postwar Tokyo, he’s dutiful and (sorry) dogged. But when he embarks on a murder case that affects him directly, Murakami becomes more frantic, more like the criminal he’s pursuing. More like a stray dog.

The 1949 movie, one of Kurosawa’s earliest, begins with a small crime, when a pickpocket swipes Murakami’s gun during a crowded bus ride. The detective needs to find the weapon, which he learns now belongs to a killer. Like Murakami, the murderer is a former soldier who has suffered since the war ended, and both men are self-destructive.

Based on an actual story, “Stray Dog” is powerful because it builds on an awareness of the desperation that accompanied Japan’s early adjustment to defeat in the war. During his search, Murakami descends into a city that seems to be staggering through a fallout of immorality and violence. Kurosawa blurs the line between right and wrong, showing the ambiguities of the times.

Even Murakami’s motivations raise questions about the war’s aftermath. He tells his partner (Takashi Shimura) that he became a cop to fill the moral vacuum and anger he felt after returning home. Murakami confesses that he might have turned to crime, like the killer (Ko Kimura) he’s trailing, if he hadn’t become a cop.

Along the way, we’re treated to sensual Kurosawa imagery. Murakami tramping through the Tokyo ghetto, disguised as a criminal. The blase chorus girls barely getting through a comic Broadway-style dance routine. The speedy shots of a Japanese baseball game. The final confrontation between Murakami and the murderer in a deserted field.

“Stray Dog” is one of Kurosawa’s more simply enjoyable films. He and screenwriter Ryuzo Kikushima never lose sight of the components that make a good crime movie: The characters are authentic, the locales colorful and surprising, and the plot has a steady velocity leading up to a satisfyingly just resolution.

“Stray Dog” (1949), directed by Akira Kurosawa. 122 minutes. Not rated.