The fishing boat reversed out of Cave 6.

Ashalina was still holding together reasonably well. Teacher Cheng was worse off — perhaps because of his age, he kept drifting in and out of consciousness, his mind clouded and his energy spent.

The boat stopped in front of the seven cave entrances.

Pan Xiaoxin looked uncertainly at Bai Youwei. “Youwei, which cave do we go into this time?”

They had already passed through Caves 4 and 2. Now Cave 6 was blocked to them, and they faced a choice all over again.

Bai Youwei looked at the cave entrances ahead and asked Pan Xiaoxin: “Xiaoxin, what pattern do you see between 4 and 2?”

Pan Xiaoxin thought for a moment. “Both are even numbers… and there’s only one number between them?”

Bai Youwei said: “Counting from right to left, between 4 and 2 there’s a 3. If the next cave follows the same pattern, counting forward from 2, which cave should we choose?”

“…7?” Pan Xiaoxin wasn’t sure.

Ashalina asked: “How confident are we about 7?”

“Hard to say.” Bai Youwei lowered her eyes and spoke softly. “When I was in the water below just now, I saw ouroboros serpents painted on the hull — seven of them. Near the ouroboros were merfolk designs, as if… once you stray from the ouroboros’s path, you’re attacked by merfolk.”

Pan Xiaoxin hadn’t gone overboard, so he hadn’t seen the patterns. Hearing this, everything clicked into place: “I understand — seven ouroboros serpents correspond to the seven cave entrances, is that right, Youwei?”

Bai Youwei inclined her head slightly and murmured in agreement: “Yes. The very first time we faced the seven cave entrances, no matter which one we chose, we didn’t encounter any merfolk. That’s because we were at the serpent’s head — every serpent’s head offered us safety. But once we went deeper and entered the serpent’s belly, we committed ourselves to one closed, looping path. We must follow the route of that particular ouroboros exactly. Stray from it, and we lose its protection.”

A-Long couldn’t help but ask: “But how do we know what that particular serpent’s route is? Are there any clues in the design?”

This was precisely what troubled Bai Youwei most.

Because the patterns on the hull showed a tangle of snakes wound around each other, and with the lighting so poor, it was genuinely difficult to make out the details. On top of that, after several merfolk attacks on the hull, the designs had been badly damaged in places — whole sections of iron plating had peeled away.

“Each ouroboros should have its own distinct pattern… I couldn’t make out obvious clues, but they were all patterned in black and red — alternating sections — and if the head is black, then the tail must be red, the colors cycling perfectly.”

Ashalina fell into thought. “If the order of the caves also cycles like the colors, then starting from Cave 4, going forward two numbers each time gives us: 2, then 7, 5, 3, 1, 6, and back to 4. We’d need to pass through caves eight times in total to cycle back to the original Cave 4.”

Bai Youwei nodded. “That’s exactly what I mean.”

After a pause, she added: “Counting from right to left, between 4 and 2 there is one number. Counting from left to right, between 4 and 2 there are exactly four numbers.”

1 — 2 — 3 — 4 — 5 — 6 — 7.

Ashalina nodded in understanding. “Got it. You mean, whatever cave you start with, the next cave is determined by how many intervals away it is. If we had started with Cave 1, the next would be 3, then 5, 7, 2, 4, 6, and back to 1 — still eight cycles to complete the loop.”

“That’s only one possible version of the pattern,” Bai Youwei said, her voice growing quieter. “Whether the color clues actually dictate the cave order — let’s hear what everyone thinks.”

Ashalina thought for a moment, then looked at A-Long: “Go down and check — count how many color segments there are on those ouroboros serpents.”

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