Security - Breach Secret

Anyone please bring back the security system with secret code!

The security system had been breached and they were unable to determine how many employees had viewed the confidential information that was now being shared all over the office. Suddenly, one of the security guards burst through the door and shouted that they have a breach! Someone has hacked into our system! The security team arrived minutes later, but when they entered the room where the test subject had been kept, they found nothing. Even more shocking was that there were no signs of a struggle or any evidence that someone had even been there.

But what happens when the most advanced security system in the world is breached? What happens when you're facing an adversary who knows exactly how to get around your defenses? You could be in big trouble.