Dramas like
Flower of Evil

The best answer if what gripped you was not knowing whether to trust the person you were rooting for. A small town, two men who are both plausibly monstrous, and a script that keeps making you complicit in your own suspicions. Same accumulation of dread out of ordinary domestic detail rather than set pieces, and a much better handle on why a community would rather the truth stayed buried. Difference: no marriage and no romance at all, so you lose the warmth that made Flower of Evil bearable between the frights.

Slow start Episode 3, the point at which you stop trusting both leads at once.

For the identity question specifically. It asks whether a person can be born a monster, refuses to let you settle on an answer, and pulls the same trick of making you re-read every earlier scene once you know more. Difference: it is considerably nastier, and it turns into a different show around episode twelve. Flower of Evil ultimately protects its family. This one is willing to take everything.

Hooks early Episode 2, once the killer and the two men chasing him are locked into the same story.

The grown-up version of the procedural half. A prosecutor who cannot feel much of anything and a detective who feels everything, working a case that is really about institutional rot. If the coincidences and the twists you saw coming bothered you, and they are the weakest thing about Flower of Evil, this is the show that never once insults you. Difference: it is cold on purpose. No mature romance, no domestic warmth, nothing to hold on to but the plot.

Hooks early Episode 2, once the first autopsy contradicts the official story.

Psychopathy handled as work rather than spectacle. Korea's first criminal profilers sitting in rooms with people whose thinking they have to model, and a quiet insistence that understanding a killer is not the same as excusing one. It goes straight at the question Flower of Evil raises about what sits underneath a learned personality. Difference: episodic, unhurried, deliberately unglamorous. No ticking clock, nobody's spouse in danger.

Hooks early Episode 2, once the first interview subject starts talking and the method becomes visible.

The odd one here, and it earns the slot: a romance-forward show with a thriller subplot that is not decoration. If the appeal was two people protecting each other while something ugly closes in, this gives you that with the proportions reversed. Difference: it is a warm, funny show about a cram school and a side-dish shop, and the menace is a subplot rather than the premise.

Slow start Episode 3, once the side-dish shop and the cram school collide properly.

If the marriage was the point. Two survivors of the same disaster, years later, neither healed, being extremely careful with each other in a way that reads as love long before anyone says so. Same register as the best scenes between these leads: adults handling damage without announcing it. Difference: no crime plot and no deception, and the grief has one clear cause rather than a hidden life.

Slow start Episode 3, once the shared history behind the collapse becomes clear.