Sidney found it a little difficult to take up the fun with her erstwhile chums where she had left off. When she stopped at the Calkins’ house directly after breakfast, Mart coolly declined to go anywhere with her, and smiled scornfully at her bare legs.

“I s’pose your million-dollar friend is otherwise engaged today!”

Sidney truthfully admitted that she was. “She’s gone to Chatham with her mother to see some people they know. And I’m glad. I’ve been just dying for a good swim. Let’s go out to the Arabella this morning.”

But Mart declared she was tired of all that. In fact she was tired of doing lots of the silly things they’d been doing. She’d promised Gert Bartow to go there right after lunch.

Sidney had no choice but to go on alone in search of Lav. She was discouraged to the point of tears. Yet she knew in her heart that she deserved Mart’s coldness. She remembered how she had felt once when Nancy had deserted her for a new girl at Miss Downs’. And it had seriously threatened their friendship.

As she wandered slowly toward the town Sidney wondered what Mart and Gert Bartow were going to do. Gert Bartow was a girl of nineteen at least, and much more grown up than even that. Mart had pointed her out to Sidney. Sidney wished Mart had asked her to go with her to Gert’s. She felt very lonely.

Perhaps she had spoiled everything. Pola would come back, of course, but, somehow, Pola’s glamour had faded. After all, what, besides tons of candy and quarts of sweet mixtures and much glitter, had there been to it? The sweets and the glitter and Pola’s endless confidences of “men” had left Sidney jaded and bored, though she did not know it; she did know that she was suddenly lonely for Mart and Lav and the stimulating pastimes they seemed to find always right at hand.

As she approached Rockman’s, wandering there from force of habit, she saw Lav pushing off in a dory. She ran down the wharf, hailing him.

“Oh, Lav, take me with you!” she pleaded, breathlessly.

He hesitated a moment before he swung the dory back to the wharf. Something of the look Mart had given her flashed into his eyes.

Then: “Come on if y’want to,” he answered ungraciously.

As she sat down in the bow of the boat Sidney wanted to cry more than anything else, but Lav’s dark face suddenly reminded her of what Aunt Achsa had told her. Perhaps he had been out in the sand dunes last night, lying on his face, sobbing aloud! She began chattering with resolute cheerfulness.

“Isn’t it hot this morning, Lav? Where are you going?” Lav answered shortly that he was going out to the Arabella. Sidney noticed a book in his pocket, but said nothing. She ventured other remarks concerning the activities in the bay to which Lavender answered in monosyllables, if at all.

“Oh, look, the Puritan’s in, Lav!” And even to this Lavender only grunted: “It’s been in two days!”

By the time they reached the Arabella Sidney’s remorse was yielding to a spark of indignation. Lav needn’t be quite so mad for, after all, it had been his own precious Mr. Dugald who had thrown her and Pola so constantly together! And if Lav had not hidden himself away he most certainly would have been included in all the plans. It was not fair in Lav to act so cross.

“I know you came out to read, Lav, and I’ve some thinking to do, so I’m going up in the bow and leave you quite to yourself,” Sidney said as they boarded the Arabella, and if in her tone there was something of Mart’s tartness, it may be forgiven for Sidney had been punished enough.

“I don’t care if you hang ’round,” Lav conceded. “It’s too hot to read, anyways. I thought maybe there’d be a breeze out here. What’s that?” For he had suddenly spied an object lying on the deck close to the rail as though it had dropped there from someone’s pocket.

At almost the same moment Sidney spied it, too. Both darted for it. Lavender reached it first and picked it up and examined it with frowning eyes.

“It’s a knife!” cried Sidney, at his elbow.

“Sure it’s a knife. Anybody can see that. What I want to know—”

“Let me look at it. Isn’t it Mr. Dugald’s?”

“No, it isn’t Mr. Dugald’s. He hasn’t been out here for a week. And that knife wasn’t here yesterday for I’d a’ seen it.”

“Let me look at it, Lav,” pleaded Sidney, for Lav, a curious expression on his face, had covered the knife with his hand.

“It’s funny, that’s all I got to say. I mean—how it come here.”

“Lavender Green, show me that knife this minute! You act so mysterious and I have a right to know why.”

Slowly Lavender placed the knife in Sidney’s eager hands. It was an ordinary case knife such as the fishermen carried, but Lavender pointed to two initials that had been carved on the case.

“J.S.”

“J.S.” repeated Sidney; then she cried: “Why—J.S.! That’s Jed Starrow!”

“Sure it’s Jed Starrow!”

“But how did it get on the Arabella?”

“That’s what I’d like to know.”

“He’s been on the Arabella, Lav!”

“Or someone of his gang.”

“Isn’t that funny? What would he come here for?”

Lavender was silent. And Sidney, staring at him as though to read from his face some explanation, suddenly fell silent, too. The secret that Cap’n Davies had laid upon her weighed heavily. She wished she could tell.

“Sid, I haven’t played square,” Lavender suddenly blurted out, flushing. “We promised to tell one another if any one of us found out anything and I did—and I didn’t tell!”

Lavender’s admission faded beside the fact that he knew something.

“Oh, what?” Sidney cried.

“I wasn’t going to tell you. I thought you didn’t care anything about the pirates any more. And the laugh’s sort o’ on me, anyway, because I thought we were all crazy to suspect Jed Starrow.”

“Tell me quick, Lav,” commanded Sidney, quivering with excitement.

Lav leaned against the rail. To tell his story meant confessing his state of mind.

“I guess I’ve been sore because you and Mr. Dugald fooled ’round with those new folks. Jealous. I get that way lots of times—all hot inside because I’m different. And I go off somewhere alone and stay there until I fight it down.”

“I know, Lav. Aunt Achsa told me. Did you go to the dunes?”

“One night I did. Stayed there all night. But one evening I went out on the breakwall. There’s a place out there where the rocks are piled so’s to make a cave. I used to play there a lot when I was a little kid. I crawled into it. And I hadn’t been there very long when I heard somebody talking—two men. They were up close so’s I heard everything they said.”

“And what did they say, Lav? Oh, tell me quick!”

“I could only get scraps of it. I didn’t dare look, I didn’t dare move. But one fellow called the other Jed. I heard ’em say something about ‘risk’ and a ‘stranger from Boston asking too many questions ’round Rockman’s to be healthy,’ and Jed Starrow—I’m dead sure it was his voice—said, sort of blustering like, ‘Let them search the Puritan! They won’t find anything on her now!’ And the other fellow answered him: ‘There’s too much in this, Jed, to take any chances.’ That’s what they said, Sid, and then they went on.”

“Oh, Lav, they’re pirates!”

“Well, not exactly pirates, but they’re up to something that’s sure. Maybe they’re rum-runners. There’s a lot of that going on. I thought you were crazy, but I guess you weren’t.”

Sidney’s lips trembled with eagerness. As long as Lavender knew what he knew she felt that she would be justified in telling him what Cap’n Davies had told her.

“It isn’t rum—Lav,” she whispered, “It’s diamonds!”

“Diamonds! Oh, go on, where did you get that stuff?”

“It’s diamonds, Lav.” Then Sidney solemnly repeated what the old Captain had told her concerning the letter and the reward. “He asked me not to tell a soul, but you’re different because you know. And he said that the reward would be posted everywhere in two weeks at least and it’s that long now. Everyone will know soon.”

“Sid, five thousand dollars!” Lavender whistled.

“If someone ’round here’s doing it Cap’n Davies wants to catch him himself. He says he doesn’t want the reward but he wants to punish the man who’s hurting the honest name of this part of Cape Cod. I think that’s a grand spirit.”

Lavender’s shoulders lifted. Why couldn’t someone else save the fair name of Cape Cod—someone like a crippled boy whom most of the towns-people looked upon as a loafer?

“I’d like to catch ’em, myself,” he said slowly in such a low voice that Sidney barely caught the words.

“Oh, Lav, why not? We have as good a chance as anyone, knowing as much as we do. What’ll we do first?” For Sidney was ready for adventure.

Suddenly Lavender realized that he was gripping the knife in his hand. He looked down at it.

“What we ought to do first is to find out how this knife got here. Let’s put it where we found it and go back around the other side of that schooner so’s no one on the Puritan’ll see us. Then we can come out late this afternoon and if it’s gone—well, we’ll know someone came to look for it!”

“And then we’d know for sure that someone had been on the Arabella.”

“That’s the idea. You get on quickly for a girl, Sid. Come on, now, we’ll pull the dory round to the starboard side.”

Sidney caught herself tiptoeing across the deck of the Arabella. In her excitement she scarcely breathed. Every move, every act, was fraught with significance. Lavender took the precaution to beach the dory at an abandoned wharf near Sunset Lane.

“Just as well not to show ourselves ’round Rockman’s.”

“When can we go out to the Arabella?”

“Not ’till four o’clock. We can go out to swim just like we always do. Even if they see us they won’t think it’s funny for us to do that. They’d think it funnier if we didn’t.”

Sidney admitted the truth of this, but wondered how she could live until four o’clock!

As they walked up Sunset Lane Sidney reminded Lavender that, because of their promise, they ought to tell Mart. But when they stopped at the Calkins’ house they found that Mart had already gone to Gert Bartow’s.

“Oh, dear,” sighed Sidney, with an added pang of remorse.

At four o’clock Sidney and Lavender went out to the Arabella to swim as they had done always before Pola’s coming. Except for a brightness in Sidney’s eyes, an alertness about her whole body, and the occasional significant glances that passed between them they both appeared quite normal. Lav talked casually of the heat of the day.

“Gee, the water’ll feel great. This is the hottest day we’ve had yet.”

“I can’t wait to get in.” Most certainly Jed Starrow, had he been listening, could not have guessed how closely Nemesis pressed upon his heels!

Lavender pulled up alongside of the Arabella and deliberately made the boat fast.

“We got to act as though we haven’t found the knife, y’see,” he warned. “As though we were going just swimming.”

In her eagerness to board the Arabella Sidney stumbled. Lavender had to clutch her to keep her from tumbling into the water.

“Oh!” They both cried in one sound as they clambered to the deck—for the knife was gone!

“Well, that means they’d been on the Arabella. Jed Starrow dropped that knife and he missed it and came back to look for it!”

“Lav, I believe they’ve hidden their treasure on the Arabella!” Sidney still reverted to the more romantic terms of buccaneering. “Let’s look for it now!”

“With ’em watching maybe from the Puritan? I guess not. We got to go ahead and swim the way we always do, Sid. Don’t let’s even appear to be talking about anything. Come on, I’ll beat you in!”

For the space of the few minutes while the water closed about her with delicious coolness Sidney forgot everything in an intoxication of delight. Presently she came back to the Arabella and climbed aboard with a sigh of utter content. “Thank goodness I haven’t any complexes,” she laughed, shaking the salt drops from her bobbed head. “And now what?”

Lavender pulled on the light sweater he had worn over his bathing suit.

“When it gets dark I’m coming out to the Arabella and stay all night. Maybe they’ll come back and I’ll find out why. That fellow said something ’bout Rockman’s not being safe. They’ll learn the Arabella isn’t safe either!”

“But Lav, I’m coming with you!”

“You can’t. And this isn’t any work for a girl to get mixed up in.”

Sidney drew herself to her full height.

“Lavender Green, if you think you’re going to lose me now you’re mistaken. I guess we went into this in a sort of partnership and it’s going to hold. I found out just as much as you did! And if you come out to the Arabella, I’m coming, and Mart, too, if she’s home.”

Lav still hesitated.

“Aunt Achsa won’t let you. How’d you get away?”

This staggered Sidney for a moment, then she thought of a “way.” This was Wednesday night and Miss Letty had said that on Wednesday night she was going to drive to Truro and that Sidney might go with her. From Truro Miss Letty was going on to Wellfleet. Aunt Achsa would think Sidney wanted to see Cap’n Davies again. She explained all this breathlessly to Lavender. “This is important enough to warrant a fib. And when it’s all over Aunt Achsa will understand. Let’s go home now and find Mart.”

Unwillingly Lavender conceded Sidney’s right to share with him his night’s vigil at any cost. Again they beached the dory near Sunset Lane.

Now they found Mart at home. Sidney put her head in the door, made certain that gran’ma was not in hearing, and cried “Hook!”

Mart had only to look once at Sidney’s face to know that something had happened. Sidney dragged her out to the Lane and there she and Lavender, in words as quick as pistol shots, told the story.

“Meet us down on the beach near Milligan’s at eight o’clock,” Lav whispered, as they parted.