“Yes,” growled the young man, brusquely.  He turned and began to swim in the opposite direction, up the cove.  The girl looked after him, raised a puzzled eyebrow, and then, with a shrug, waded into the water.  The next time the assistant looked at her, she was swimming with long, sweeping strokes down the narrow creek to the bend and the deep hole at the end of the wharf.  Round that bend and through that hole the tide whirled, like a rapid, out into the miniature bay behind Black Man’s Point.  It was against that tide that Seth Atkins had warned him.

And the girl was swimming directly toward the dangerous narrows.  Brown growled an exclamation of disgust.  He had no mind to continue the acquaintance, and yet he couldn’t permit her to do that.

“Miss Graham!” he called.  “Oh, Miss Graham!”

She heard him, but did not stop.

“Yes?” she called in answer, continuing to swim.  “What is it?”

“You mustn’t—­” shouted Brown.  Then he remembered that he must not shout.  Shouting might awaken the lightkeeper, and the latter would misunderstand the situation, of course.  So he cut his warning to one word.

“Wait!” he called, and began swimming toward her.  She did not come to meet him, but merely ceased swimming and turned on her back to float.  And, floating, the tide would carry her on almost as rapidly as if she assisted it.  That tide did not need any assistance.  Brown swung on his side and settled into the racing stroke, the stroke which had won him cups at the athletic club.

He reached her in a time so short that she was surprised into an admiring comment.

“Oh!” she exclaimed, “you can swim!”

He did not thank her for the compliment.  There was no time for that, even if he had felt like it.

“You shouldn’t be here,” he said sharply.

She looked at him.

“Why, what do you mean?” she demanded.

“It isn’t safe.  A little farther, and the tide would carry you out to sea.  Come back, back up to the cove at once.”

He expected her to ask more questions, but she did not.  Instead she turned and struck out in silence.  Against the tide, even there, the pull was tremendous.

“Shall I help you?” he asked.

“No, I can make it.”

And she did.  It was his turn to be surprised into admiration.

“By Jove!” he panted, as they swung into the quiet water of the cove and stood erect in the shallows, “that was great!  You are a good swimmer.”

“Thank you,” she answered, breathlessly.  “It was a tug, wasn’t it?  Thank you for warning me.  Now tell me about the dangerous places, please.”

He told her, repeating Seth’s tales of the tide’s strength.

“But it is safe enough here?” she asked.

“Oh, yes! perfectly safe anywhere this side of the narrow part—­the creek.”

“I’m so glad.  This water is glorious, and I began to be afraid I should have to give it up.”