Ed Küpfer’s review published on Letterboxd :
It's a measure of how good the run of Korean thrillers has been over the last twenty years that a merely mediocre one counts as a real disappointment. I'm used to being challenged by Korean thrillers, but this film doesn't have that level of ambition. This story of a desperate father searching for his kidnapped son using "lucid dreaming" (and later "dream sharing") reminds me nothing more than of Michael Crichton's lesser techno-thrillers filled with jargon and technobabble pertaining to fake invented technology that everybody just happens to know the rules of, as if it was a real thing. Entertaining enough, I guess.