Lee Haeun's peaceful life fell into pieces the night her twin Chaeeun disappeared without a trace. With no way to contact her sister and rent to pay, Haeun has little choice but to go to Chaeeun's company, disguised as Chaeeun herself! Things get even more complicated when she falls for the aloof Oh Joowan, her sister's colleague and mortal enemy! Will Haeun successfully dupe everyone, including her newfound crush, or will the consequences of going twincognito be too much for her?