The passage inside was a narrow tunnel; the front section still held water requiring a swim, but the rear slowly receded until it only allowed single-file crawling. Once the Mermaid reached the dry area, her tail transformed into legs, and the four of us proceeded on all fours, using all limbs to navigate the confined space.

After crawling for perhaps ten minutes, Wang Jue and I were breathless, the tunnel filled only with our gasping. Hou Dayong and the Mermaid, however, showed no signs of fatigue. Secret places, it seemed since antiquity, were always connected by tunnels, perhaps to remain hidden, though this made the crawling dreadfully difficult.

Finally, the tunnel ended. We saw Hou Dayong and the Mermaid ahead, one after the other, emerging from the opening and straightening up onto level ground. Just as I thrust half my head out of the exit, something happened between the two of them.

The Mermaid produced a dagger from somewhere and plunged it into Hou Dayong’s left chest. Completely unprepared, Hou Dayong choked out a mouthful of black blood from the sudden attack. Startled, I scrambled onto level ground and, using the bottle strapped to my right wrist, punched the Mermaid on the back of her head. It is said the most vulnerable spot on a person is the back of the head, the location of the hypothalamus. In an emergency crouch, the hands instinctively cover this area—a reaction that shows how crucial that spot is.

However, the Mermaid’s nape seemed less fragile than a human’s. I struck her through the bottle, and she turned to face me, showing no sign of pain or distress. She merely clutched the dagger, advancing on me step by measured step. Hou Dayong seemed badly wounded, half-sitting on the ground clutching his chest, black blood oozing between his fingers.

I slowly retreated until my back hit the wall. Touching it, I felt a fine dust of lime powder coating the surface. I thought about grabbing some in my hand to smear into her eyes if she charged, blinding her so I could counterattack. As I formulated this plan, Wang Jue, standing behind her, seized another dagger and violently stabbed it into her left back.

A doctor is a doctor; this thrust was remarkably precise. The Mermaid’s eyes widened, scarlet bloody froth bubbling from her mouth as she pitched forward onto the floor.

It turned out this room was an armory. A wooden rack lined the wall to the left of the tunnel entrance, neatly displaying an assortment of weapons. The Mermaid, having exited first, had the opportunity to reach the arsenal first. She hid the dagger behind her, waiting for Hou Dayong to emerge so she could strike for a decisive victory. As it happened, after my attempted surprise attack failed, Wang Jue successfully retaliated.

After securing the Mermaid, Wang Jue and I hurried to Hou Dayong’s side. His eyes were half-closed, his mouth full of black blood, and the wound continued to pour forth. Although Wang Jue was a doctor, even the most skilled cook cannot work without rice; all three of us were wearing form-fitting suits, and the Mermaid had no clothing. There wasn't a scrap of fabric in the room, making it impossible to staunch Hou Dayong’s bleeding.

“What do we do now?” I asked anxiously.

Hou Dayong gripped my wrist weakly. “Do you remember the time we used you for a sacrifice?”

The words brought that unpleasant memory instantly flashing through my mind, and I frowned. “What about it?”

“Stab your palm with the dagger… drip the blood onto… my wound.” Hou Dayong exerted every ounce of strength to finish the sentence; it was clear he had little energy left.