According to Their Own Instincts summary: Kang Yu-Jin, an executive director at Shin-A Food, has lived by the belief that proving herself through numbers and skills is everything.To seize control of "Shin-A Food", her ultimate goal, she proposes a contract marriage to Ki Seung-Hyun, the president of SOO ENM. Ki Seung-Hyun, who lives while concealing his beastly nature, readily accepts her proposal to use him and cooperates by acting as a loving partner.