The Grand Duke Yulikian lost his parents in a power struggle due to his uncle's schemes who wanted to seize the throne. Following his mother's dying wish to survive, he frequents the slums daily and lives recklessly in order to avoid attention. But he's tormented by his inability to act despite his growing desire for revenge.

That's when "Crazy Maddie," a con artist from the slums with a suspicious past, approaches him. Although Yulikian initially wants nothing to do with her, he has a brilliant idea after witnessing her instantly dispatch two assassins in an alley and disappear. Thus, in order to ruin his reputation, he enters a contract marriage with Maddie.