The tunnel extended downward, forming a straight, inclined staircase.
Cai Qin walked in front, illuminating the path with her flashlight, and soon they arrived at an iron door.
Next to the iron door was something resembling a wall-mounted phone. Cai Qin lifted a metal plate on it, and immediately, buttons with phone numbers appeared. Cai Qin pressed a few numbers, and Fang Yi, following behind, also saw clearly.
"These numbers seem a bit simple, don't they?" Fang Yi said, having memorized them after one glance.
Without turning her head, Cai Qin replied, "Though simple, it's just a random door-opening code, different every time." She took out her phone, waved it in front of Fang Yi, and added, "Once we enter, a new code will be sent to my phone."
Fang Yi wiped his brow; it was just like a verification code.
After Cai Qin entered the code, a biometric scanner extended from above and scanned both her eyes.
Then, the iron door slid sideways, revealing a brightly lit corridor.
