A cold draft blew past his cheeks, ruffling his hair. 

Why was there a draft in here? 

Xia Lei observed the entrances of the six passageways closely and soon discovered that drafts of air were coming from the first, third and sixth passageways. The second, fourth and fifth ones had no drafts of air and no sound came from them. He focused his gaze on the second passageway. According to da Vinci’s map, the second passageway was the correct one to take. 

Xia Lei did not step onto the “correct” pathway right away either. He used his previous method to test the accuracy of the map. He threw heavy weapons into the other five passageways, then activated his X-ray vision to look at the end of the passageways. He got the results of his observations fairly quickly, and he was puzzled. There were no problems at all with the six passageways in front of him, and not one of them had any hidden traps. 

What was going on here? 

Just as Xia Lei moved to enter the second passageway, his head suddenly felt heavy. He shook his head to clear it, but it did not help....