Caspian City is a thriving global enterprise, secretly ran by the Choi dynasty. Kai is the newest member of the Messenger Society. The secret group that delivers letters from the Chois to the public leaders. Text messages and emails can be traced. The Messenger Society delivers letters that can't be. Kai's first mission is to deliver a letter to Beomgyu Choi. What happens when the person who was supposed to be hidden, gets noticed by the youngest heir?