Lee San (Lee Min-ho) and A-Yo (Wallace Chung), former Interpol agents, are hired as bodyguards by a reporter to protect his source. Starting with this "simple mission," they find themselves caught up in something bigger than themselves, but along the way they’ll find allies—the Bounty Hunters, led by Cat (Tiffany Tang). Together, they’ll have to solve the case of the terrorist attacks on hotels to clear their names. Will they succeed? Who is behind these attacks?