Chaos erupts in Cho Miran's department for the Secret Service on her second day there when notorious enemy spymaster Oh Sehun turns himself in at their local headquarters. Twelve hours later, he is dead, leaving the Secret Service reeling with the realisation that they have a mole – which could end up bringing the country and its war effort to its knees.  It is up to Cho Miran, her mentor Do Kyungsoo, and the rest of their department to discover which spy has turned rogue and to stop