"None of your business!" snapped the man. "And I want to tell you one thing more. You've got to quit trailing after us, too!"
"Suppose we refuse?" asked Andy.
"Then it will be the worse for you. Meldrick, just run that brass cannon over on this side."
A moment later the muzzle of a small brass gun was pointed menacingly at our heroes.
"There's my answer," went on the mysterious man. "If you persist in following us you'll be plugged below the water line. Now you go back where you came from, and keep away. Don't try to meddle with what doesn't concern you."
"This does concern us—or, rather a friend of ours," said Frank determinedly. "And what's more, we're going to swear out a warrant for your arrest for setting fire to our boat with a bale of hay."
The man on the rail started.
"Are you going to turn back?" he shouted.
"No!" declared Frank.
"Get ready to fire," said the scoundrel calmly.