You know this if you have followed three or more corruption K-dramas: South Korea's legal system is apparently either broken, malfunctioning or has been compromised by collusion between public servants and prominent businessmen.

And this poses a serious problem for a legal thriller that has the misfortune to come after standard-bearers such as The Chaser (2012) and Signal (2016) and in a year that has thrown up two beat-the-system hits, Innocent Defendant and Whisper. How can it address similar issues without sounding like a broken record?

Stranger, the tvN corruption drama, pulls it off impressively, finding a distinctive voice to tell a deeply human story.

It works at the basic level as a gripping whodunnit of corpses and nubile bodies, but also asks a larger question as a character drama. Namely, are things so dire in South Korea that the only person who can reboot the system is an emotionless man who has the social skills of a robot and is derided as not quite human?

This would be Hwang Shi Mok (Cho Seung Woo), a prosecutor who had a partial lobotomy when he was in his teens to treat a sound-sensitivity disorder. But the operation has left him aloof, incapable of processing feelings - his and other people's - and prone to rubbing people the wrong way.

He is the kind of guy who inspects a dead inmate's body and tells a prison guard coolly: "Thank you for showing me." Then he questions the distraught widow in a way that is so tone-deaf as to be cruel.

By the same token, however, he is also a purer spirit than his colleagues. He doesn't get mixed up in social-climbing and case-rigging, but keeps a laser-beam focus on his investigations, facts and reason.

The show begins with the killing of a businessman who is down on his luck. Hwang, the first man to arrive at the scene of the murder, arrests a television repairman with the help of a female detective, Han Yeo Jin (Doona Bae), but the suspect cries foul.

The case soon spirals: The victim turns out to have procured young women for high-ranking officials, possibly including both Hwang's and Han's bosses; he was threatening to blow the whistle on the men before his death; and so on.

But what is as fascinating, if not more, is the camaraderie that grows between Hwang and Han, whose warmth and openness contrast with, but also complement, his social ineptness.

She studies his behaviour too and notes how he does have feelings, after all. For example, when he misjudges the ability of a colleague who didn't graduate from the same top school as him, it is more an emotional than a rational decision, she points out.

And he admits: "I can't believe the only thing I can feel is a sense of superiority."

The drama doesn't judge, though. The people in the show run the gamut, from the misguided to the inconsistently kind and brave. But, you know, they're only human.