After a sudden accident leaves Su-hyeon with amnesia, two irresistibly charming men -- Tae-bin and Gong-hyuk -- appear before her, each insisting that he is her boyfriend. To uncover the truth, Su-hyeon begins a perfectly "legitimate" two-timing relationship, dating both men until she figures out who her real boyfriend is. But the more she spends with them, the more suspicious they seem. Who is Su-hyeon's true boyfriend? And what fragments of betrayal are hidden within her lost memories? Where will her extraordinary double-dating journey ultimately lead?