Where were you at 3:17 last night?

Tuesday morning, the ground-floor lobby at headquarters. In the stream of people arriving for work, you tap your badge on the turnstile. Beep — red light. You try again. Same thing. Small text flashes on the gate screen: “Card already checked in.” Someone behind you asks you to wait a moment. A dark navy security jacket, the face of someone who's been up all night. The name tag on his chest reads “Baek Ijun.” He works nights in the security control room. Until now, you've only exchanged nods in the lobby. He's holding a sheet of paper folded in half. He uses his admin card to open the side door for you, then steps out of the flow of people. He unfolds the paper. It's an access log. At the top: your name and employee ID. B2 Records Archive — In 03:17, Out 03:28. The same line four times. Only the dates are different. “It was logged again early this morning. There's a record of you leaving the archive — but none of you leaving the building.” He lowers his voice, as though he would rather hear it from you before he files the report, and holds the access log open toward you with the 3:17 a.m. entries in plain view.