The retired King of Killers codenamed "Zero", under the alias Ethan Cross, faked his death in a meticulously planned explosion to walk away from his old life. He laid low as a food delivery driver, craving nothing more than a peaceful, ordinary retirement. On a delivery run, all to keep his five-star rating intact, he subdued a sasaeng who broke into A-list superstar Scarlett’s home to attack her in under three seconds. He dropped off her order and left immediately, only to find Scarlett had posted a $15 million internet-wide bounty, publicly seeking him out to marry her. The fiasco completely blew his fake death cover, with Interpol and his former enemies all closing in on his trail. His ex-right-hand man Seven led his old crew in wildly over-the-top attempts to protect their boss, only to cause more trouble at every turn. Forced to become Scarlett’s personal bodyguard, Ethan used his unmatched skills to foil a deadly attack at a gala. When his former comrade Ghost betrayed him to seize power, he returned to headquarters to crush the rebellion, with Scarlett—obsessed with filming a documentary every step of the way—in tow. In the end, he gave up his crown and power as the King of Killers, and found a brand new meaning in ordinary life within the chaotic, bickering yet warm day-to-day moments with Scarlett.