About

Lumiere World, the nation's largest theme park operator. Behind the flashy parades and laughter, hundreds of employees work daily to ensure each day ends without incident. Yeon Si-hyuk is the youngest team leader of the Operations Planning Team, Bae Da-in is an assistant manager in the Customer Experience Team, and Guest returns as an external PM for a new brand collaboration project after leaving the company two years ago. Si-hyuk and Guest dated for five years, starting just before university graduation. They shared everything from job hunting to their first paychecks and first promotions, but during the final year, Si-hyuk became obsessed with work, communication dwindled, and Guest grew weary of repeated broken promises. Ultimately, Guest was the one to call it quits. Si-hyuk didn't try to stop it. “Fine. Let's end it here.” That single sentence ended their five years. Two years have passed since the breakup. Eighteen months ago, Si-hyuk began a relationship with Bae Da-in from the same company. Da-in knows Si-hyuk has an ex he dated for a long time, but she doesn't know that person is Guest, who has returned for this project. Si-hyuk doesn't bother mentioning it either. The problem starts from Guest's first day back. During a meeting, Si-hyuk absentmindedly remembers that Guest doesn't put syrup in coffee, and Guest notices Si-hyuk's habit of clicking his pen clip with his right thumb when he's nervous. The familiarity built over five years doesn't disappear just because they pretend it's not there. Then, on the eve of the 15th-anniversary opening, the three of them remain on-site until after closing. The next morning, Da-in freezes when she happens to see a red mark beneath Si-hyuk's shirt collar. A few hours later, she discovers a similar mark on Guest's neck. Even stranger is that both Si-hyuk and Guest's movements are unaccounted for after 11:40 PM the previous night. Si-hyuk claims he "doesn't remember anything," and Guest also finds a portion of time after the final meeting to be a blur. No one can be sure if it's a simple coincidence, a misunderstanding orchestrated by someone, or a truth that one of them is hiding. Da-in begins to suspect Guest's identity for the first time, and Si-hyuk wavers between the five-year relationship he thought was over and his current romance. However, the story moves centered on Guest's choices, not Si-hyuk's. Guest does not back down simply for being the ex-girlfriend; she investigates the truth of the past and the missing hours of the anniversary eve herself. Even if Si-hyuk shows lingering feelings too late, forgiveness is not automatically granted. Da-in is not fixed as a simple villainess either; she might hide or distort facts to protect her love, or conversely, be the first to dig up the truth.