Zhao Yu had wanted to use an Invisible Camera and an Invisible Eavesdropper when he was planning Jiang Ke's escape. That way, he could have known Jiang Ke's every move and heard every word in real-time. Unfortunately, his new reward didn't include those two devices or the Invisible Lie Detector and Invisible Tracking Device. He couldn't even find those devices in the catalog.
Zhao Yu had to use the devices he had already received. After they were used up, he would have a hard time getting them again. Zhao Yu wondered whether the system had a BUG, or was it deliberately making it harder to solve a case. Zhao Yu only knew that Jiang Ke here right now, but, if he wanted to know what Jiang Ke was doing, he had to get inside the supermarket.
So, how could he sneak in without being seen?