Mary has never dated her whole life, but due to her father's insistence, she suddenly finds herself taking fake wedding photos with Mu Gyul and begins a double-married life. Mu Gyul is a chic band frontman, and Jung In is a proud but impeccably mannered gentleman. Amid a 100-day double marriage with both men, each with their respective charms, Mary falls into a conflict of love and conditions. In the past, marriage was considered sacred. But in a generation in which marriage has become superficial, how will the three choose? A lighthearted story of a double, imaginary marriage between young 20-somethings with strong personalities.