“Here’s a delightful morning, doctor,” he sang out in a fine, brassy, resonant, seafaring voice; “sort of day for a trip to the lower river, hey? Hallo, Polton! Coming down to take the bread out of our mouths, are you? Ha, ha!” The cheery laugh rang out over the river and mingled with the throb of the engine as the launch moved off from the pier.

Captain Grumpass was one of the Elder Brethren of the Trinity House. Formerly a client of Thorndyke’s he had subsided, as Thorndyke’s clients were apt to do, into the position of a personal friend, and his hearty regard included our invaluable assistant.

“Nice state of things,” continued the captain, with a chuckle, “when a body of nautical experts have got to be taught their business by a parcel of lawyers or doctors, what? I suppose trade’s slack and ‘Satan findeth mischief still,’ hey, Polton?”

“There isn’t much doing on the civil side, sir,” replied Polton, with a quaint, crinkly smile, “but the criminals are still going strong.”

“Ha! mystery department still flourishing, what? And, by Jove! talking of mysteries, doctor, our people have got a queer problem to work out; something quite in your line—quite. Yes, and, by the Lord Moses, since I’ve got you here, why shouldn’t I suck your brains?”

“Exactly,” said Thorndyke. “Why shouldn’t you?”

“Well, then, I will,” said the captain, “so here goes. All hands to the pump!” He lit a cigar, and, after a few preliminary puffs, began: “The mystery, shortly stated, is this: one of our lighthousemen has disappeared—vanished off the face of the earth and left no trace. He may have bolted, he may have been drowned accidentally or he may have been murdered. But I’d rather give you the particulars in order. At the end of last week a barge brought into Ramsgate a letter from the screw-pile lighthouse on the Girdler. There are only two men there, and it seems that one of them, a man named Barnett, had broken his leg, and he asked that the tender should be sent to bring him ashore. Well, it happened that the local tender, the Warden, was up on the slip in Ramsgate Harbour, having a scrape down, and wouldn’t be available for a day or two, so, as the case was urgent, the officer at Ramsgate sent a letter to the lighthouse by one of the pleasure steamers saying that the man should be relieved by boat on the following morning, which was Saturday. He also wrote to a new hand who had just been taken on, a man named James Brown, who was lodging near Reculver, waiting his turn, telling him to go out on Saturday morning in the coast-guard’s boat; and he sent a third letter to the coast-guard at Reculver asking him to take Brown out to the lighthouse and bring Barnett ashore. Well, between them, they made a fine muddle of it. The coast-guard couldn’t spare either a boat or a man, so they borrowed a fisherman’s boat, and in this the man Brown started off alone, like an idiot, on the chance that Barnett would be able to sail the boat back in spite of his broken leg.

“Meanwhile Barnett, who is a Whitstable man, had signalled a collier bound for his native town, and got taken off; so that the other keeper, Thomas Jeffreys, was left alone until Brown should turn up.

“But Brown never did turn up. The coast-guard helped him to put off and saw him well out to sea, and the keeper, Jeffreys, saw a sailing-boat with one man in her making for the lighthouse. Then a bank of fog came up and hit the boat, and when the fog cleared she was nowhere to be seen. Man and boat had vanished and left no sign.”

“He may have been run down,” Thorndyke suggested.