relief “It was only the door swung open, it’s that heavy—that’s all.”

“Blow the door!” said another growling voice; “blessed if I didn’t think it was a fair cop that time.”

They closed the door again. Gerald did not mind. In fact, he rather preferred that it should be so. He didn’t like the look of those men. There was an air of threat about them. In their presence even invisibility seemed too thin a disguise. And Gerald had seen as much as he wanted to see. He had seen that he had been right about the gang. By wonderful luck—beginner’s luck, a card-player would have told him—he had discovered a burglary on the very first night of his detective career. The men were taking silver out of two great chests, wrapping it in rags, and packing it in baizedj sacks. The door of the room was of iron six inches thick. It was, in fact, the strong-room, and these men had picked the lock. The tools they had done it with lay on the floor, on a neat cloth roll, such as wood-carvers keep their chisels in.

The men were taking silver out of two great chests

“Hurry up!” Gerald heard. “You needn’t take all night over it.”

The silver rattled slightly. “You’re a rattling of them trays like bloomin’ castanets,” said the gruffest voice. Gerald turned and went away, very carefully and very quickly. And it is a most curious thing that, though he couldn’t find the way to the servants’ wing when he had nothing else to think of, yet now, with his mind full, so to speak, of silver forks and silver cups, and the question of who might be coming after him down those twisting passages, he went straight as an arrow to the door that led from the hall to the place he wanted to get to.

As he went the happenings took words in his mind.

“The fortunate detective,” he told himself, “having succeeded beyond his wildest dreams, himself left the spot in search of assistance.”

But what assistance? There were, no doubt, men in the house, also the aunt; but he could not warn them. He was too hopelessly invisible to carry any weight with strangers. The assistance of Mabel would not be of much value. The police? Before they could be got—and the getting of them presented difficulties—the burglars would have cleared away with their sacks of silver.

Gerald stopped and thought hard; he held his head with both hands to do it. You know the way—the same as you sometimes do for simple equations or the dates of the battles of the Civil War.

Then with pencil, note-book, a window-ledge, and all the cleverness he could find at the moment, he wrote:

“You know the room where the silver is. Burglars are burgling it, the thick door is picked. Send a man for police. I will follow the burglars if they get away ere police arrive on the spot.”

He hesitated a moment, and ended—

“From a Friend—this is not a sell.”

This letter, tied tightly round a stone by means of a shoelace, thundered through the window of the room where Mabel and her aunt, in the ardour of reunion, were enjoying a supper of unusual charm—stewed plums, cream, spongecakes, custard in cups, and cold bread-and-butter pudding.

Gerald, in hungry invisibility, looked wistfully at the supper before he threw the stone. He waited till the shrieks had died away, saw the stone picked up, the warning letter read.

“Nonsense!” said the aunt, growing calmer. “How wicked! Of course it’s a hoax.”

“Oh! do send for the police, like he says,” wailed Mabel.

“Like who says?” snapped the aunt.

“Whoever it is,” Mabel moaned.

“Send for the police at once,” said Gerald, outside, in the manliest voice he could find. “You’ll only blame yourself if you don’t. I can’t do any more for you.”

“I—I’ll set the dogs on you!” cried the aunt.

“Oh, auntie, don’t!” Mabel was dancing with agitation. “It’s true—I know it’s true. Do—do wake Bates!”

“I don’t believe a word of it,” said the aunt. No more did Bates when, owing to Mabel’s persistent worryings, he was awakened. But when he had seen the paper, and had to choose whether he’d go to the strong-room and see that there really wasn’t anything to believe or go for the police on his bicycle, he chose the latter course.

When the police arrived the strong-room door stood ajar, and the silver, or as much of it as the three men could carry, was gone.

Gerald’s note-book and pencil came into play again later