"This is going to be a unique sort of burglary," he continued. "Trot out what you've got in the way of plate, and I'll take my pick of it as a kind of fee in reward for my night's service. If there is one soft place in my heart, it is for antique silver. Take your time--we are not in the least likely to be interrupted."

With his coat off and his shirt sleeves turned up, Carrington set to work in earnest. Once he had plunged headlong into the business, he seemed to have lost all his nervousness and hesitation. One after the other the great wooden cases were turned out and examined by Anstruther as eagerly as a schoolboy pores over something new in the way of a bird's nest. Presently he held aloft a magnificent specimen of a silver dish. It was perfectly plain: fine old hammered silver, bearing a quaint design around the edge.

"Benvenuto Cellini for a million," he cried. "Dish and ewer, together with a set of the finest posset cups I've ever seen. How much over ten thousand pounds would this fetch at Christie's? Well, I'm very sorry for the late owner, but exceedingly pleased so far as I am concerned. I'll take this for my fee, Carrington."

The two dived into the strong room again, where they appeared to be overhauling other boxes of treasure. The gleams of the electric light fell upon the service of plate which Anstruther had so greatly admired. By its side, in strange contrast, laid a piece of cotton waste with which Anstruther had wiped his hands a minute or two before. Without a word of warning to his companions, Seymour darted across the floor of the vault; and, seizing the cotton waste, proceeded to rub it vigorously over the surface of the service of plate which Anstruther had marked down for his own.

His conduct was so unexpected and so peculiar, that Jack and Rigby could only look at one another in astonishment. They did not know in the least what to make of this extraordinary manœuvre on the part of their colleague. But there was evidently much method in his madness; he was not in the least likely to run the risk of detection to gratify an apparently meaningless whim. He was back again an instant later, and Jack could hear him chuckling to himself as if he had accomplished something quite out of the common. He seemed to feel that some explanation was necessary.

"I dare say you thought that peculiar," he said; "but you will understand all in good time. I didn't go out of my way to spoil everything for the mere sake of playing amateur housemaid."

Apparently the task which Anstruther and Carrington had set themselves was finished by this time, for they came out of the strong room empty handed. All the same, their figures appeared to be pretty bulky, and doubtless their pockets were well filled with illicit gain.

"But you don't mean to carry that stuff home," Carrington protested. "Well known as you are, it would be an act of criminal folly to carry that plate through the streets at this time of the morning. As to myself----"

"But have you no private safe of your own?" Anstruther asked. "The same remark you made to me just now applies to you. Is there anything more to wait for?"

Carrington disappeared within the strong room again for a last look round, followed by Anstruther. They had no sooner disappeared than Seymour was on his feet again, making hurriedly for the stairway leading to the counting house. He had not been gone many seconds before there came stumbling noisily down the stairs the form of one of the night watchmen, rubbing his eyes drowsily, and asking what was going on. It was quite evident to Rigby and Jack that Seymour had deliberately aroused the sleeping man for some subtle purpose of his own. The man cried out again to know what all this meant, and Carrington and Anstruther came darting from the strong room.