Mrs. Bobbsey at first did not know whether Freddie was playing some of his make-believe games, or whether he really had caught a fish.

Certainly something seemed to be pulling on the line he held out of the porthole, but then, his mother thought, it might have caught on something, as fishlines often do get caught.

"I've caught a fish! I've caught a fish!" Freddie cried again. "Oh, please somebody come and help me pull it in!"

Flossie was so excited--almost as much as was her brother--that she forgot all about her lost doll.

"Have you really caught a fish?" asked Mrs. Bobbsey.

"I really have! I guess maybe it's a shark or a whale, it's so big, and it pulls so hard!" cried Freddie.

And, really, the line that was wound around his hand was pulled so tight, and stretched so hard, where it went out of the hole and down into the ocean, that Freddie could not lower his fist.

"Oh, Freddie!" cried his mother. "If you have caught a fish it may cut your fingers by jerking on that line."

"Well, I--I caught something!" Freddie said. "Please somebody get it off my line. And hurry, please!"

By this time Nan and Bert had run down into the storeroom. They saw what was going on.

"Are you sure you haven't caught another hat?" asked Bert, as he remembered what had once happened to his little brother.

"It doesn't pull like a hat," Freddie answered. "It's a real fish."

"I believe he has caught something," said Mr. Chase, the engineer, as he ran in from the motor room. "Yes, it's either a fish or a turtle," he added as he caught hold of the line and took some of the pull off Freddie's hand. "Unwind that cord from your fingers," he told the little boy. "I'll take care of your fish--if you really have one."

"Could it be a turtle?" asked Nan.

"Yes, there are lots of 'em in these waters," the engineer said. "But I never knew one of 'em to bite on just a piece of string before, without even a hook or a bit of bait on it."

"Oh, I got something on my line for bait," Freddie answered.

But no one paid any attention to him just then, for the engineer, gently thrusting the little boy aside, looked from the porthole himself, and what he saw made him cry:

"The little lad has caught something all right. Would you mind running up on deck and telling Captain Crane your brother has caught something,"

said Mr. Chase to Bert. "And tell him, if he wants to get it aboard he'd better tell one of the men to stand by with a long-handled net. I think it's a turtle or a big fish, and it'll be good to eat whatever it is--unless it's a shark, and some folks eat them nowadays."

"Oh, I don't want to catch a shark!" exclaimed Freddie.

"It's already caught, whatever it is," said Mr. Chase, "It seems to be well hooked, too, whatever you used on the end of your line."

"I tied on a----" began Freddie, but, once again, no one paid attention to what he said, for the fish, or whatever it was on the end of the line, began to squirm in the water, "squiggle" Freddie called it afterward--and the engineer had to hold tightly to the line.

"Please hurry and tell the captain to reach the net overboard and pull this fish in," begged Mr. Chase of Bert. "I'd pull it in through the porthole, but I'm afraid it will get off if I try."

All this while the _Swallow_ was moving slowly along through the blue waters of the deep sea, for when the engineer had run in to see what Freddie had caught he had shut down the motor so that it moved at a quarter speed.

Up on deck ran Bert, to find his father and Captain Crane there talking with Cousin Jasper.

"What is it, Bert?" asked Mr. Bobbsey.

"Oh, will you please get out a net, Captain!" cried Nan's brother.

"Freddie has caught a big fish through the porthole and the engineer--Mr. Chase--is holding it now, and he can't pull it in, and will you do it with a net?"

"My! that's a funny thing to have happen!" said Mr. Bobbsey.

"I'll get the net!" cried Captain Crane. "If your brother has really caught a fish or a turtle we can have it for dinner. I wouldn't be surprised if it was a turtle," said the captain to Bert's father. "There are plenty around where we are sailing now, and they'll sometimes bite on a bare hook, though they like something to eat better. What bait did Freddie use?" he asked.

"I don't know," Bert answered.

By this time Captain Crane had found a large net, which had a long handle fast to it, and also a rope, so that if the fish were so large that the handle should break in lifting it from the water, the rope would hold.

With the net ready to dip down into the water, Captain Crane ran along the deck until he stood above the porthole, out of which ran the line.

The fish, or whatever it was, was still fast to the other end of the strong cord.

"Haul it up as close as you can to the side of the boat!" called the captain to the engineer, who thrust his head partly out of the round hole. "Then I'll scoop it up in the net. Watch out he doesn't get off the hook."

"That's the trouble," said the engineer. "I don't believe Freddie used a hook. But we'll soon see."

Up on the deck of the _Swallow_, as well as down in the storeroom, where Freddie, his mother and the others were watching, there was an anxious moment. They all wanted to see what it was the little boy had caught.

"Here we go, now!" cried Captain Crane, as he lowered the long-handled net into the water near the cord. The captain held to the wooden handle, and Mr. Bobbsey had hold of the rope.

Through the porthole Mr. Chase pulled on the cord until he had brought the flapping, struggling captive close to the side of the motor boat.

Then, with a sudden scoop, Captain Crane slipped the net under it.

"Now pull!" he cried, and both he and Mr. Bobbsey did this.

Up out of the blue sea rose something in the net. And as the sun shone on the glistening sides Freddie, peering from the porthole beside the engineer, cried:

"Oh, it's a fish! It's a big fish!"

And indeed it was, a flapping fish, of large size, the silver scales of which shone brightly in the sun.

"Pull!" cried the captain to Mr. Bobbsey, and a few seconds later the fish lay flapping on deck.

Up from below came Freddie, greatly excited, followed by his mother, Nan, Flossie and Mr. Chase, Flossie chanting loudly: "Freddie caught a fish! Freddie caught a fish!"

"Didn't I tell you I caught a fish?" cried the little boy, his blue eyes shining with excitement.

"You certainly did," his father answered. "But how did you do it, little fat fireman?"

"Well, Captain Crane gave me the fishline," Freddie answered.

"Yes, I did," the captain said. "He begged me for one and I let him take it. I didn't think he could do any harm, as I didn't let him take any sharp hooks--or any hooks, in fact."

"If he didn't have his line baited, or a hook on it, I don't see how he caught anything," said the engineer.

"I did have something on my line," Freddie exclaimed. "I had--I had----"

But just then Flossie, who had been forgotten in the excitement, burst out with: