On a night when rain that steals memory drenches the city, adult mage pharmacist Ryu Si-gyeom faces a newly arrived investigator with an antidote nearly finished in his hands. Neither can easily trust the others methods or hidden motives. But the truth behind the rain that steals someones memories cannot be reached by just one of them. A restrained set of principles, an uneasy partnership, and small kindnesses shake their guard in this rivals to lovers romance.