This early Kurosawa effort floats stylistically somewhere between the film noir and neo-realism, incorporating the best from both worlds to elaborately craft a landscape (both physical and social) of post-war Japan. It's only been 4 years since the dreadful A-bombings and the subsequent defeat of Japan in WW2 and both the country and the people are deeply scarred. War veterans return home to find a country torn by poverty and as the saying goes, desperate conditions demand desperate measures.
A very young Toshiro Mifune plays the greenhorn detective who has his gun stolen and spends the rest of the movie trying to track down the culprit. As it turns out the culprit is a war veteran just like Mifune's character, only where the latter tried to do good and found an honest job, the former opted for the easy way out and became a criminal, using the stolen gun to rob and kill. This adds an additional layer of motivation for detective Sato. Not only does he have to restore his honour (ironically symbolised by the lost gun which he tries to retrieve), but also redeem himself by bringing the killer to justice. What makes matters worse for him is that every time his stolen gun is fired someone dies or gets injured, which adds another burden of guilt on the shoulders of the young detective.
The story might appear too moralistic and convenient (both antagonist and protagonist share a common background, being war veterans, making the distinction of good and bad all too easy), but it has to be seen in the context of the times. Mifune says that there are no bad people, only bad situations. But as his detective collaborator on the case remarks (played by the great Takashi Shimura, who also starred in Seven Samurai) he faced the same bad situation and made something good out of it. Kurosawa here neatly balances the social climate of post-war Japan and the conditions of the times with personal responsibility.
Story-wise it's a worthy effort, but like Rashomon, it sounds a little bit better than it actually is. Not that Stray Dog is a bad movie by any means, but clocking in at 2 hours it starts to drag near the middle. There are some nice set-pieces that showcase Kurosawa's growing talent (like the phone scene in the hotel where he uses inter-cutting to great effect) and the performances are solid all around. There's also a silent 10 minute montage of location footage shot in rundown neighborhoods as Sato searches the black market for his gun, which serves as a poignant snapshot of Japanese history.
Kurosawa would go on to achieve international acclaim with his next movie, Rashomon, but Stray Dog already shows that he was destined for great things. Compared to later entries in his filmography Stray Dog appears to be a minor entry, but it's still well worth the time to discover.