"But that doesn't help us any," Harry protested. "There is no opening to the outside world except for the water!"
"Let's go along back and look over the walls more carefully," offered Francois. "Maybe we overlooked an opening in the hurry!"
Accordingly the boys slowly retraced their steps, examining every inch of the walls. Shortly after passing the place where Ned had fallen into the current of water, Jimmie, who had been in the lead, turned back with a muffled hiss. He snapped the switch on his searchlight.
"What is it, Jimmie?" queried Jack, following the leader.
"I see a light in the passage!" replied Jimmie. "It flickers like a candle light and seems to be dodging about.
"Maybe it's the Duke's private ghost!" whispered Jack with a grin.
"Hush!" hissed Jimmie. "Cut out that nonsense!"
Proceeding cautiously, the boys indeed saw a faint reflection on the side wall. In a moment they heard voices.
The light came from a small opening about shoulder high. Through this opening also came the sound of conversation. In an instant Jimmie was peering through the hole. He dropped back shaking with excitement.
"Guess who the ghosts are!" he gritted in a whisper. "You'd never believe it! The Rat and our old friend Hungry are in there!"