Se-eun is a janitor who is always the first to arrive at the pool where she works. One day, she runs into an old friend who is now a swimming instructor.
26-year-old Yong-jun hasn't quite figured things out yet – but when he reluctantly agrees to start working part-time for his parents' lunchbox shop, a chance encounter suddenly breathes new life and possibility into his summer. Making a delivery to a swimming pool, he meets and immediately falls for Yeo-reum: the sunny and devoted sister to Ga-eul, a gifted swimmer who is deaf and training to qualify for the Olympics. The two sisters communicate in Korean Sign Language, which Yong-jun is fluent in too. Chasing his heart, Yong-jun sparks a journey of discovery in all three of their lives.
Disguised under the shadows of a mask, a crew of desperados band together under the leadership of a criminal mastermind known only as “The Professor” to pull off the biggest heist Korea has ever seen.
