On another in a long line of sweltering summer days in post-war Japan, rookie cop Murakami (Toshiro Mifune), exhausted from a night without sleep, boards an uncomfortably packed city bus after leaving the gun range, and upon deboarding, realizes his colt has been pickpocketed. On foot, he chases after the man he suspects is the culprit, but loses him. Murakami is an honest, upright new recruit, so he immediately reports the incident to his chief, who isn’t anywhere as concerned as Murakami is about there being one more gun out there amid the general public. From the chief’s perspective, the difference is marginal, but to Murakami, it’s devastating. Any blood drawn by the gun will be on his hands, and the guilt bearing down on him is as oppressive as the brutal seasonal heat.
Initially, Murakami seeks out the thief on his own. A colleague helps to lead him to the realization that there might have been an accomplice, and sure enough, when Murakami sifts through mugshots of previously booked pickpockets, he recognizes a woman from his miserable bus ride. He tracks her down and tails her around the city in one of two extended montages in which Kurosawa dexterously condenses action down into a suspenseful string of shots. The second such montage comes shortly thereafter as Murakami puts on dirtied up civilian gear and prowls the backstreets and alleyways of downtown, hoping he’ll be approached by a pistol dealer. Murakami picks up a trail that looks like it could lead him to the thief, and joins up with the more experienced officer Satō (Takashi Shimura, another Kurosawa regular) to see the trail to its end.
The colt does indeed inflict harm before Murakami is able to retrieve it, and that only strengthens his single-minded determination to find the criminal. But how much violence or illegality is he really preventing even if he does get the gun back in his holster before it’s been emptied of bullets? With his obsessiveness, it’s as if he thinks all crime and wrongdoing rested squarely on his shoulders, and there’s something heartening about his optimistic albeit naive thinking that he alone can prevent so much suffering. The culprit, after all, turns out to be a desperate veteran, only one of many in the aftermath of traumatizing war. A commentary on the social ills of post-war Japan thus lies beneath what on its surface is an expertly crafted film noir.