Signal is sending shivers up my spine — not the scary-frightening type of shivers, but those when u sorta foresee what bad things will happen, and you can’t do anything about them. Which is ironic. Given that the whole narrative rests on a 2015 cop giving away hints to a 80s/90s cop about cases which happened in the latter’s era in order to solve cases — aka have a better ending than the past.
I find Signal kinda similar (in the meta sense) as Nine: Nine Times Nine Time Travel, where the protagonist tries to correct a wrong in the past, possibly succeeding, but also ending up making something or someone worse off. The infamous Gyeonggi-nam do case (eps3/4) is a huge foreshadowing of what will happen in eps 5/6, where events get seriously fouled up and one of our major characters die.
To make it even clearer, our protagonist (or one of them), Jae-han, even voices out what we dread — is the walkie talkie thing a curse? Should he have never picked up that equipment and got lured into using Hae-young’s “hindsight” to solve his own cases? Kinda true — if you tally the misfortunes and body count. From using that walkie talkie, Jae-han’s crush and a young girl have died. Plus he framed the wrong man for a crime, and ended up (indirectly) killing his female partner (Soo-hyun) years later.
Then again, the walkie talkie has also benefited Hae-young. Using Jae-han as a supplement to the cases’ write ups (and Jae-han being a first hand witness/ detective in the unsolved cases is a HUGE help), Hae-young and team have managed to nail a serial murderer and a kidnapper who have evaded punishment for years.
But it doesn’t take long for both men to recognize the wallkie talkie bridge as a double edged sword. Now that Jae-han has really fouled up in arresting the wrong man and (again, indirectly) causing the death of his young daughter, and Hae-young recognizes he played a part in it by his offhand remark of fingerprints on letterboxes (leading to same wronged man accidentally killing his team leader), the two guys have to race against time to correct their “wrongs”.
Not easy, considering how similar both men are in terms of characters and situations. Although they are good detectives, both are disillusioned about the police force and more importantly, both are shunned by their colleagues thanks to their bull headedness and lack of tact. And ironically, both will have an uphill task of trying to unmask the culprit of eps5/6. Jae-han will have a hard time arresting rich boy Se-kyu in his time, and Hye-young will have difficulties trying to re-open the burglary case, whom everyone in the force deems as closed and done with.