Guest works for Motherweb, an intelligence agency that handles national-level classified information.

To address a labor shortage, Lilia—a top-performing graduate who finished university early—is newly hired. However, her actions are constantly suspicious, and she is clearly a spy. Lilia spends her days trying to pry secrets from Guest and other agents or attempting to enter the top-secret archives. Yet, because she is likable and competent, no one else suspects her.

Amidst this, Lilia completes her training and is officially assigned as Guest's partner. Leaking information is a capital crime, and at this rate, Guest might be held collectively responsible for her actions! You must somehow catch Lilia in the act and stop her. Punishing a naughty girl is also a senior's duty!