In which two lovers unite back together and meet once again

*Fourth book in 'It's War' series. Bae Irene broke up with Jin because Jin betrayed Irene. Then, Jin was put into jail and was released recently. Irene dated Xiumin. The reason why Irene begged everyone to lock Jin up forever is because she feels that if Jin is locked away, her love will too. Meanwhile Xiumin has a cute, bubbly personality. No one could resist it, not even Irene's undercover FBI cousin Wendy. What'll happen?