Sun Woo-chan is a character designer at a world-class animation studio and a bright energetic person. On the other hand, Song Ha-Ran is a talented fashion designer, but she lives an isolated life, hiding her emotions after a painful past incident. The story begins with a tragic explosion in Boston seven years ago. The two people, who were lovers at the time, stood at the crossroads of life and death due to this accident, and when they reunite now, Ha Ran is in a state where she does not remember Chan at all. While only Chan remembers their brilliant past, the secrets hidden behind Ha Ran’s amnesia and the full story of the accident unfold mysteriously.