Xiao Wei is a fox demon who feasts on human hearts in order to maintain his clean, youthful appearance. When General Pei Rong rescues him from the remains of a battlefield and offers him a home, trouble begins. The hearts of Pei Rong and her husband, Wang Sheng, are Xiao Wei's biggest desire - however, both are desired for very different reasons.

民国沪上，军阀幼子慕容清峄（张凌赫 饰）因被抱错而受尽养父虐待，少年出逃时被任素素（王楚然 饰）所救，却累及其家族遭灭顶之灾。经年重逢，二人暗生情愫，但任素素为救他人，毅然假死遁逃，留慕容清峄沉沦于失爱之痛。三年后任素素回归，却成了慕容清峄的准大嫂。如今的二人，一个满是被背叛的怨，一个藏着难以言说的痛，在试探与拉扯间爱恨交织。当误会渐解、深情重燃，国难却至。慕容清峄与任素素怀揣必死决心对抗强敌，他们的命运将走向何方？
剧集根据匪我思存原著小说《如果这一秒，我没有遇见你》改编。