Ryu and Cheon bond as best friends and rivals from school years into adulthood. Their complex relationship evolves through affection, competition and reconnects when tragedy strikes.

The journey of two friends who have an enduring, complicated love-hate relationship. They find their lives intricately linked as they cross each other's paths through various phases in life. Ryu Eun-jung, a charming and honest woman, forms a close bond with Cheon Sang-yeon, who becomes her best friend and rival. The series explores the intricacies of their complex friendship as they navigate the challenges of life, feeling both care and envy for each other. The story traces their friendship from their school days to their twenties and thirties, showing how their bond changes over time. At 42 years old, they reunite in the face of a profound challenge: Sang-yeon's battle with cancer. The touching narrative delves into their shared past, their separate paths to becoming a screenwriter and a successful film director, and the enduring impact they've had on each other's lives.