"What's the matter?" he asked, turning to Sammy. "Are you afraid to go down?"
"No—no—of course not!" exclaimed Sammy, quickly. "But the stairs are so narrow——"
"Pooh, they're wide enough for us three," said Frank. "Here, I'll go first if you like—I'm not afraid."
"Neither am I!" retorted Sammy, as he stepped up between his chums once more.
"Let's all go down together," suggested Bob. "I don't believe that there's anything down there, but——"
Suddenly a deep, hollow groan sounded from somewhere in the lower region of the ship.
"Hark!" cried Sammy.
"Oh, we all heard it!" gasped Bob. "No need to hark! I'm going up on deck."
He turned to go back up the few steps he had come down, and Sammy went with him. Only Frank stood there.
"Say, what's the matter with you two fellows?" he asked.