Immediately behind them came Adrien and Lady Constance.  The latter had chosen to represent “Miranda,” and her loveliness seemed almost supernatural.  The pale gold of her hair and the perfect shell-pink of her complexion were set off to advantage by her gown, which, simple as it was, yet showed by that very simplicity the hand of the master by whom it had been designed.  It was of palest green satin, edged with chiffon in such a way as to represent the crested waves, relieved here and there by pink sea-shells and tiny wreaths of seaweed; while her only ornaments were pearls, the gifts of her guardian.  It was little wonder that Adrien had been unable to express the admiration he felt, when he looked upon her fair beauty, which was now, however, covered by a velvet mask.

He himself had taken the character of Charles the First, and, with his dark, deep eyes and melancholy face, fully looked the part of the unhappy monarch.  There was a faint murmur of admiration as he entered, for every detail had been so carefully copied, from the lace collar to the jewelled order across his breast, that it was as if Van Dyck’s famous picture itself had stepped down from its frame.

Unconscious of the attention they provoked, Adrien led Lady Constance out to the first dance, and opened the ball with her.

Miss Penelope was in the seventh heaven of delight, when some little time later Adrien came up to her.

“What a magnificent sight, is it not, Adrien?” she said excitedly.  “I knew it would be a success; but really the dresses are wonderful.  Then the mystery is so delightful.  I can’t recognise any one now under the masks.  Look, who is that?” She glanced towards a lady dressed as Undine, who seemed to float by them, so light were her movements, on the arm of a Mephistopheles.

“That,” said Adrien, whose quick eyes readily penetrated the majority of the disguises, “that is—­yes, I cannot be mistaken—­Ev—­Lady Merivale.”

His voice dropped slightly as he spoke the name; for he had not expected that she would accept Miss Penelope’s invitation, and was surprised by her presence.

“Who is the Mephistopheles?” asked his aunt.

Adrien glanced after the couple rather puzzled.

“I don’t know,” he admitted frankly.

“It is something, a shadow only, like Mr. Vermont,” suggested Miss Penelope.

“It cannot be he,” said Adrien, “he is not coming to-night.”

Lord Barminster, who had approached in time to hear this speech, looked affectionately at his son, and Adrien caught the glance and understood it.  But without making any comment, he went in search of his partner for the next waltz.

Meanwhile, Undine and Mephistopheles had seated themselves in the deep recess of one of the alcoves.

“May I get you an ice, madam?” asked the Mephistopheles in a queer, strained voice.

Undine turned her face towards him, and her eyes flashed curiously through the mask.