There’s no lock Detective Do-Bin Kim can’t open. With his unique ‘opening’ ability, he can unlock anything -- even people -- to get the information he needs to hunt down criminals and solve crimes. Enter Locker -- his polar opposite and his enemy. When Locker uses her ability to ‘lock’ a witness and prevents Kim from accessing key information in a crucial case, they plunge into a cat-and-mouse game with justice itself at stake. When two equal forces collide, who will emerge the victor?