Fenestra had not taken time to lower the door behind him. A light shone from an underground room at one side of the main passageway, and she could hear the man’s heavy boots scuffing on a cement floor.
Penny considered going after Jerry and decided against it. Fenestra’s frantic haste suggested that he might not linger long in the cave. What could he be doing beneath ground?
With Jerry so near, she felt that it would not be too dangerous to investigate. Warily she tiptoed down the steps.
A low, rounding doorway opened from the descending passage. Peering into the dimly lighted room, Penny did not immediately see Peter Fenestra.
Instead her gaze roved about the walls of what appeared to be a workshop. Tools were neatly arranged over a bench, while a cupboard of shelves contained miscellaneous mechanical parts.
At the far end of the cave stood an urn-like contrivance which the girl took to be an electric furnace. An armored cable ran from it to a heavy wall switch having two blades and a sizable wooden handle. Plainly it was designed to carry a very heavy current.
Peter Fenestra came from behind the furnace. Penny saw him throw the switch. Almost immediately she heard a low hissing sound from the interior of the metal oven. Slowly the furnace heated, and soon glowed weirdly.
As she pondered what the man could be intending to do, she heard a slight sound at the stairway entrance. Thinking that Jerry had returned, she started up the steps. Not one figure but three loomed in the doorway!
Penny flattened herself against the dirt wall. But she could not avoid being seen. A flashlight beam focused upon her, and the next instant a revolver muzzle bit into her side.
“Keep quiet!” she was ordered in a whisper. “You won’t be hurt!”