Shell Island is really only an island in name. A narrow creek which fills and empties with the incoming and outgoing tides divides it from the mainland. A bridge spans this chasm over which flows a constant stream of motor and driving parties from all the villages and summer resorts up and down the coast.

Just at sundown, as the “Comet” took the steep road down the cliff to the bridge, a big touring car shot past.

“Oh, dear,” exclaimed Nancy, “I did hope we would leave all care behind when we came away, and now I am perfectly certain that Belle Rogers was sitting on the front seat of that automobile. I suppose she’ll be floating around the ballroom in blue chiffons this evening.”

“Is she a care?” asked Billie, who had a placid and rather masculine way of forgetting all about the people she didn’t like.

“Oh, I don’t mind her, only she always makes me feel like a rag picker’s daughter.”

“I think she’s over-dressed,” put in Billie. “I should feel utterly foolish with all that finery and jewelry on me. When papa and I used to buy my clothes, he would say: ‘Suppose we stick to plain white, daughter, and skip the furbelows. We can’t go very far wrong if we do that, and if my little daughter begins to put on ruffles and puffles and falals without anybody’s advice but mine, I’m afraid she might be taken for a walking fashion plate and some one will try to stand her up in a shop window.”

Nancy laughed.

“I think you have the prettiest dresses I ever saw, Billie, but I am glad Miss Campbell has persuaded you to stop dressing so much like a boy. Lace collars are lots more becoming than those stiff linen ones.”

“They were chokers,” answered Billie, good-naturedly, as the car drew up at the steps of the hotel immediately behind the automobile which had passed it on the road.

Belle and her party were waiting on the piazza, the women in long pongee coats with the very latest motor bonnets and veils.

“Those are her rich friends, the Jordannes,” whispered Nancy, in awed tones. “They used to be just plain Jordan before they made so much money.”

“I think Jordan is a much nicer name. It has such a fine Oriental sound, ‘Where rolls the River Jordan.’”

By this time several porters from the hotel had stepped to the motor car door and assisted Miss Campbell, somewhat stiff from the long ride, to alight. The girls jumped nimbly out after her and their luggage was unstrapped and piled on the ground near the Jordanne luggage. But Billie was careful to keep a firm hold on her own suit case with its precious load.

“Let the man take your bag, dear,” called Miss Campbell. “You will strain your back carrying that heavy thing.”

There was nothing for Billie to do but resign the suit case, although she tried to keep an eye on it as they followed the porter through the lobby to the elevator. Miss Campbell had telegraphed ahead for rooms.

As luck would have it, there was another elevator for luggage, and the bag was temporarily out of Billie’s sight, but her mind was soon at ease when she saw it stacked with the others in the bedroom which she and Nancy were to share.

“While we dress for dinner,” she observed, “we’ll have a talk about that jewelry. What on earth are we going to do with it?”

“Don’t you think we’d better tell Miss Campbell?” suggested Elinor.

“I suppose it would be best, but Cousin Helen does go off so about things, and I have a feeling that if she knew it she wouldn’t allow us to keep our promise to our poor beautiful lady. She would be sure to turn the box over to the police or call in a lawyer or something. And if we could only keep the box until we heard from the man in Paris, at least, we should be keeping our word about it.”

Elinor and Mary were all for telling, but the other girls were still under the spell of the very beautiful and distressed woman, and since it was mostly their affair they concluded not to tell.

You must not blame Billie for this want of frankness. Girls who have never had mothers to talk to in the intimate way that only a mother and daughter know, are apt to be reserved and self-reliant. Billie would certainly have told her father, but, then, he was in Russia.

Mary and Elinor, whose room adjoined the other, had put on their kimonos and were lolling on the beds, while Nancy with solicitous care was removing her pretty muslin frock from the valise and smoothing out the pink taffeta ribbons tenderly.

Billie knelt on the floor and opened her suit case.

“Before I undress,” she said decisively, “I’m going to take this box straight down stairs and give it to the clerk to put in the safe. Then we can spend the evening with easy minds.”

She flung back the top and sat down on the floor with a gasp.

“In the name of all the powers, this is not my suit case.”

The girls gathered around her in great excitement.

“It’s exactly like mine,” she went on, “but there are no initials on it and mine has ‘W.H.C.’ on the end.”

“Girls,” cried Nancy, flinging her bathrobe around her with a tragic gesture, “the very last person in the world we could wish to have Billie’s suit case is the very one who has it. She’ll look at everything in it; examine the underclothes to see if they are hand-made and the stockings to see if they are silk, and—she’ll open the box of jewels and read the card of the avocat from Paris and——”

“Who? Who?” interrupted the other three.

“Who but Belle Rogers,” cried Nancy, flourishing a towel in one hand and a hair brush in the other.

“Yes, that’s her costume,” admitted Mary, laughing. “Blue chiffon with a wreath of pink roses for her hair.”

She pulled up a corner of the pale blue gauzy material and pointed to a little pink wreath which lay in the folds of the dress.

“There are her blue satin slippers, No. Two’s, absolutely not a size larger,” said Elinor, pointing to the toe of a little slipper which showed at one end of the suit case.

“This is what I get for losing the keys to everything,” groaned Billie. “Telephone for a boy, quick, some one, while I fasten this thing up. Perhaps she hasn’t opened mine yet.”

“Opened it!” echoed the others. “You don’t know her.”

Presently a bell boy tapped at the door.

Billie gave him the suit case with full instructions.

“And hurry,” she added. “If you are back here in five minutes, you shall have an extra tip.”

Five, ten, fifteen minutes passed. The other girls were almost dressed, and Billie was beginning to tap the floor nervously with an impatient foot, when at last there was a tap at the door.

“Why didn’t you come sooner?” demanded Nancy and Billie in one voice.

“The young lady wouldn’t let me, Miss.”

“But what was she doing all that time?”

“I don’t know, Miss. She simply told me to wait outside. She was very angry, Miss, about her bag.”

“Angry, indeed,” answered Billie, seizing her own suit case. “At least no time was lost in sending it to her.”

The two girls opened the suit case with great anxiety. The things in it were assuredly in rather a rumpled condition. They had the appearance of having been unfolded and hastily rolled up again in new folds.

Nothing could be told about the box of jewels. They were all there apparently in a glittering bunch with the card laid on top.

“Dear me, I’m sorry that combination lock broke,” exclaimed Billie. “I don’t mind Belle Rogers looking through my clothes if it gives her any satisfaction, but I would just as soon she hadn’t looked into this box of jewels. And we can’t explain to her, because we mustn’t seem to know that she was capable of doing anything so low and common as to go through my suit case.”

She dressed herself hastily in a pretty white frock. Her smooth rolls of hair and trim braid did not need re-arranging, and she hurried downstairs to the desk with the troublesome box, which she gave into the charge of the clerk.

“These are some really valuable things,” she said. “Will you put them in your safe?”

The clerk wrapped the box up neatly in heavy brown paper, sealed it with red sealing wax, labelled it with her name and address and deposited it in the safe.

“That’s off my mind,” she said, giving a sigh of relief, just as the elevator door opened and Miss Campbell appeared with the other girls.

“Cousin Helen, you’re a dream,” cried Billie, taking her cousin’s arm. “You are like a young girl whose hair had gone and turned white in a single night.”

“Thank you, my dear, but you may be sure that if anything happened which could make my hair turn white in a night, it wouldn’t leave me any girlish looks. But why didn’t you come to my room and let me have a look at you? Are you all exactly right and in place? That’s a sweet little frock. I suppose you got it in Paris last summer. You and your father are a pair of children shopping together, I imagine. All my girls look sweet,” she added, not wishing to wound any feelings by admiring one more than another. “See this lovely dress my little Mary is wearing. Could anything be more exquisitely made than that? Your mother is a wonderful woman, child. There’s nobody like her in West Haven.”

At dinner there was another surprise for the girls. This time it was an agreeable one: four extra places at the table, and presently they were joined by four West Haven boys, looking rather embarrassed but quite happy as they shook hands with the fairy godmother of the party, Billie’s Cousin Helen.

Two of the boys we have met before, Ben Austen and Charlie Clay. The other two were their intimate friends and boon companions, Americus Brown, Nancy’s brother, known as “Merry Brown,” and Percival Algernon St. Clair, whose mother’s fancy had run riot in naming her only child. He was called “Percy” by his friends for short.

“Why, look who’s here,” exclaimed Nancy. “Percival Algernon St. Clair, why didn’t you tell us yesterday when you gave us soda water at the drug store that you were coming on this trip, too?”

“Because it was secret,” answered Percy, who was very blond and blushed easily. “Miss Campbell wanted to surprise you.”

“I thought it would be nice for my girls to have some partners for the dance to-night,” said Miss Campbell. “I wanted to see some real dancing.”

“If you want to see the real thing, then, Miss Campbell,” said Merry Brown, “if you want to see the poetry of motion, you must see Ben dance.”

“Shut up, bow-legs,” called Ben across the table. “I’ve been learning for months. I took lessons last summer.”

“Where?” demanded his friends, because at the school dances, Ben’s expression of misery was well known when he towed an unfortunate friend around the room.

“I know,” said Percy, “it’s all explained now. That’s what you were doing at the Dutch picnics every week.”

“Well, they were pretty good teachers,” replied the imperturbable Ben. “They taught me that guiding a girl in a dance was very much like sailing a boat with a windmill for a sail. You have to guide and twirl at the same time, and the more speed you make in twirling the better your dancing is.”

Everybody laughed uproariously at this description.

“Ben Austen, I didn’t expect to be treated like a windmill sail boat when I promised to give you my first dance,” announced Elinor.

“It would be better than to be treated like a stationary windmill and go turning around in one place like the Germans dance,” observed Billie.

“You may all have your choice,” said Ben. “Stationary or progressive, it’s all one to me, only remember that you have each promised to do a Dutch twirl with me.”

The ballroom was already quite filled with dancers and it seemed very bewildering and delightful to the young girls, if it was only a summer hotel with a piano and two violins and a flute for an orchestra. Ben’s Dutch whirl was so skillfully performed, because like everything else he attempted he had mastered it perfectly, that the girls found it rather exciting fun.

“It’s a regular romp,” cried Billie, who, with glowing cheeks, dropped breathlessly into a chair beside her Cousin Helen.

“Look,” whispered Mary Price, who had been dancing a quiet glide with Charlie Clay and had had a chance to notice some of the other dancers.

For some reason both their young faces turned suddenly very grave. Was it a strange, unexplained premonition that told them the most dangerous enemy either was ever to have was dancing past that moment, in floating pale blue chiffon draperies?

After the dance there was a merry supper party with sandwiches and lemonade in the grill room, and then the Motor Maids were glad enough to get to their beds.

“What a relief it is, Nancy, dear, to have that box of jewels in the safe,” said Billie sleepily, as her eyelids drooped and she settled herself under the covers.

But Nancy did not reply. She was sleeping deeply. Billie, too, was soon oblivious of everything in the world.

As the night wore on, Nancy dreamed that she was dancing the Dutch twirl in a wonderful blue gauze dress, but that the diamond necklace she wore so weighed her down that she could not breathe.

Billie also dreamed of the diamonds. They were not around her neck, but in their box, which had grown to the size of a trunk and pressed on her chest so heavily that she was suffocating.

Suddenly a great bell clanged out in the night.

Billie opened her eyes with difficulty. The room was filled with smoke and down the corridor there came the cry of “Fire! Fire!”