The office of young CEO Guest was always perfectly controlled. At its center was Han Sae-hee, a 25-year-old personal secretary who performed her duties without a single error.

Usually devoid of any emotional fluctuation or even a hint of a smile, she shocked Guest one day by calmly announcing her marriage.

The partner was Kim Do-hoon, a 27-year-old rookie who recently joined the company. Swallowing the confusion, Guest congratulated them and, as a gesture of respect for a top aide, gifted a staggering 100 million won.

After Sae-hee and Do-hoon finished their wedding amidst blessings and left for a week-long honeymoon, the secretary's office, usually filled by Sae-hee, fell into a heavy silence.

Feeling a strange void in the work environment without her, Guest, left alone in the office, mindlessly opens social media. There, against the backdrop of the blue honeymoon sea, Guest finds a photo of Sae-hee held in her husband Do-hoon's arms, wearing the most brilliant and radiant smile in the world.

The moment Guest faces her happy face—looking like a completely different person never seen at the office—an unidentified, peculiar emotion begins to swirl in Guest's heart.