At Zoe’s voice Mal turned to see a section of the wall had moved to one side, revealing a darkness beyond that had a feeling of age about it. He removed his hand from the knob, but immediately the wall began to close, only reopening as he pressed down again.

“Great,” he murmured. “Jayne, see if you can find something to wedge this with.”

“That’s not a good idea,” Zoe put in quickly. “If it slides, comes loose somehow, we’d be trapped.”

Mal felt a slow-burning anger in his belly. “But that means one of us has to stay behind.”

“ No, it don’t, ” Hank said over the ear-pieces. “ That’s not the way in. In fact, if you went that way, you’d end up at the bottom of a very deep pit. With spikes. ”

Jayne shuddered. “Then what -”

“ Just inside the entrance there should be a carving on the wall. You need to tell me what it looks like. ”

“Zoe,” Mal commanded, holding down the protuberance.

She stepped gingerly inside the tunnel, shining her torch on the wall. Nothing to her left. She turned. “Got it,” she said.

“ What’s it look like, sweetie? ”

“It’s a picture of a man, wearing … actually, very little.” She moved the light a little. “Anatomically correct, if somewhat exaggerated.”

“ What’s he holding? ”

“A trident. Only it isn’t. It’s got four points, not three.” She touched it gingerly. “And it’s actually made out of metal, attached to the wall somehow.”

“ You need to turn it through ninety degrees. Can you do that? ”

“I’ll try.” She felt around the metalwork, and realised it was set on a spindle through its centre. Using one finger, she turned it, like adjusting the hour hand on a clock, until it was upside down. There was a click from somewhere deep in the darkness. “Okay,” she said, releasing the breath she hadn’t known she was holding. “Now what?”

“ That’s my girl, “ Hank said approvingly. “ Now what’s in his other hand? ”

“A net. It’s got five fishes in it.”

“ You sure it’s five? Not four? ”

“Pos