It caught my right shoulder, danced briefly over the short stubby spikes, and died out.

Approximating my assailant's position, I lunged - and closed my fist on empty air. Two sharp daggers sprung into my hands.

"Come out, come out, whoever you are," I said in a singsong voice.

No one stirred, but the tunnel grew hot and tight. The sulphur stench worsened, making my eyes water. It was as if all oxygen was being sucked out. I spread my arms out to reassure myself ...