Ji Yoon, is a seventh-year office worker stuck in a career slump, who chooses her prickly boss, Si Woo, as the “lesser evil” to avoid the “worst.” Together, they grow to become each other’s irreplaceable “best.” Kang Si Woo, the direct supervisor of Cha Ji Yoon and a handsome man who has everything except a pleasant personality. Kang Si Woo has striking looks, an impressive physique, and a lifestyle fit for a self-care textbook, but his cold, blunt manner has earned him the nickname “the company’s worst grump.” He becomes tangled in an unusual way with Ji Yoon. Cha Ji Yoon, a hardworking professional worn down by her job and by life itself. Known for her skilled hands and exceptional work instincts, she handles tasks with ease and has earned the trust of her colleagues. However, she is facing a slump in both work and love. Into her ordinary life barges her prickly boss, Kang Si Woo.