Spanning four episodes, the miniseries features a struggling man who is subjected to a simulated reality in order to gain happiness and evade all of his sufferings.
[2][3] Living a life of sadness and debts, 33-year-old Do Kang-soo (Choi Tae-joon) works as a loan shark in Shinseong Capital for his and his father's sustenance.
His mother Lee In-sook (Nam Gi-ae) has long been away from home since when Kang-soo was still a baby due to her husband Do Jung-man's (Woo Hyun) cruelty and drunkenness.
Jung-man, now guilty of ruining his family, works for a junk shop despite his old age and declining health.
He had also been thinking so much on how to make his and his father's lives better, even contemplating on stealing money from his boss Hwang Tae-bok (Park Ho-san).
Woo presents her team's invention: a glucose-coated amino acid medicinal capsule combined with a protein from the cerebral artery that is injected to the brain to “maximize the feeling of happiness” and make a human subject believe that all of his/her desires “have come true” within a “perfect world.” Dr.
Woo takes a tomography of Kang-soo's brain and tells him that he is 96% suitable for the experiment, i.e. he can undergo the test without any problems.
Kang-soo's father learns of the accident and rushes to the hospital, mourning at the doors of the operating room.
As Tae-bok and his men are arrested, Kang-soo sees his co-worker Hong Ki-chul (Kim Kyung-nam) come out of hiding.
Kang-soo receives a call from Ki-chul, telling him that Tae-bok will soon be released due to lack of evidence and requests for them to meet.
But it is revealed that the “real” Kang-soo is lying in a sleep-like state in a room in Bliss Laboratory with tubes injecting a blue fluid—the “happiness” capsule dissolved in liquid—into his head.
The scenes starting from Kang-soo waking up in the hospital and onwards were all part of the simulated reality induced by Dr.
Kang-soo's father is seen in front of Bliss Laboratory's building holding a bracelet with a string of five digits inscribed on it.
He sees a seemingly dead body covered in a blanket being brought from the building into a Bliss Laboratory truck.
He peeks through the door's window and sees that the dead body, now enclosed in large flames, wore a bracelet like the one he is holding to.
Woo convinces Jung-man to let Kang-soo undergo the experiment, in return for a reward money to be granted to him.
Woo and her team lays Kang-soo on a bed, with small tubes connecting his head to a fluid-filled cylinder.
Woo's signal, the test starts: a “happiness” capsule is dissolved in the cylinder, and the resulting fluid is injected into Kang-woo.
Back to the capsule-induced alternate reality, Kang-soo becomes the CEO of his own company and he is ready to be married to Sun-young.
Woo about Kang-soo visiting the laboratory after reading the message from one of their flyers and declining the offer for Jung-man's sake.
He dismisses the call and spends happy times with his parents and Sun-young, taking photos at the seashore.
Back at his company, he chases a suspicious hooded man but he loses him, and he suddenly experiences a spell of dizziness.
Though he is very dizzy, he saw the hooded man approach him and telling the same warning, to “get out.” He wakes up and finds himself back at home in his bedroom with his mother.
This, she believes, will let him experience reality and let him see “what a nightmare his real life has been.” In consequence, Kang-soo's mother escapes from home, his father becomes a fourth-stage liver cancer patient, Tae-bok is suddenly resurrected and tries to catch him with his henchmen, and Sun-young changes sides and goes back to Tae-bok.
Woo rushes to the control room to increase his dosage, but the Kang-soo in the simulation begins plunging himself into the sea.
In the closing scene of the series, a photo studio is shown with a photograph of Kang-soo and his father, encased in a frame, put up on display.