“Hypnotism,” said Avery very quietly.

Piers laughed again.  “It’s a word you don’t understand, my Queen of all good fairies.  It’s only the naughty fairies—­the will-o’-the-wisps and the hobgoblins—­that know anything about it.  It’s a wicked spell concocted by the King of Evil himself, and it’s only under that spell that his prisoners ever see the light.  It’s the one ticket of leave from the dungeons, and they must either use it or die in the dark.”

Jeanie was listening with a puzzled frown, but Gracie’s imagination was instantly fired.

“Do go on!” she said eagerly.  “I know what a ticket of leave is.  Nurse’s uncle had one.  It means you have to go back after a certain time, doesn’t it?”

“Exactly,” said Piers grimly.  “When the ticket expires.”

“But I don’t see,” began Jeanie.  Her face was flushed and a little distressed.  “How can hypnotism be like—­like a ticket of leave?”

“I told you you wouldn’t understand,” said Piers.  “You see you’ve got to realize what hypnotism is before you can know what it’s like.  It’s really the art of imposing one’s will upon someone else’s, of making that other person see things as you want them to see them—­not as they really are.  It’s the power of deception carried to a superlative degree.  And when that power is exhausted, the ticket may be said to have expired—­and the prisoner returns to the dungeon.  Sometimes he takes the other person with him.  Sometimes he goes alone.”

He stopped abruptly as a hand rapped smartly on the door.

Avery looked up again from her work.  “Come in!” she said.

“It’s the doctor!” whispered Gracie to Piers.  “Bother him!”

Piers laughed with his lower lip between his teeth, and Lennox Tudor opened the door and paused upon the threshold.

Avery rose to receive him, but his look passed her almost instantly and rested frowningly upon Piers.

“Enter the Lord High Executioner!” said Piers flippantly.  “Well?  Who is the latest victim?  And what have you come here for?”

The doctor came in.  He shook hands with Avery, and turned at once to Piers.

“I have come to see my patient,” he said aggressively.

“Have you?” said Piers.  “So have I.”  He stood up, squaring his broad shoulders.  “And I’m coming again—­by special invitation.”  His dark eyes flung a gibe with the words.

“Good-bye, Mr. Evesham!” said Avery somewhat pointedly.

He turned sharply, and took her extended hand with elaborate courtesy.

“Good-bye,—­Mrs. Denys!” he said.

“I’ll come down and see you off,” cried Gracie, attaching herself to his free arm.

“Ah!  Wait a bit!” said Piers.  “I haven’t said good-bye to the Queen of the fairies yet.”

He dropped upon one knee by Jeanie’s sofa.  Her arm slid round his neck.

“When will you come again?” she whispered.

“When do you hold your next court?” he whispered back.