The Special Branch may consist of hard, resolute men well able to take care of themselves, yet Superintendent Swain was a tall, thin figure, neatly but plainly suited. He spoke quietly and, as he sat down, he turned an intelligent equine profile and gentle eyes toward us. Inspector Lestrade had warned us scornfully what to expect from a man who read Lord Tennyson’s
Idylls of the King
or Mr. Browning’s translation of the
Agamemnon
—or even Tait’s
Recent Advances in Physical Science
and Lyell’s
On Geology
. There had been a movement among his colleagues to get rid of Alfred Swain by posting him to the Special Branch. He was thought by his CID superiors to be ‘too clever by half.’ He certainly gave the impression of a man who would rather have come to tea to discuss the novels of Mr. George Meredith—one of Sherlock Holmes’s unaccountable enthusiasms. Holmes took to him from the start. As his grey eyes studied my friend intently, Swain picked his words carefully, almost fastidiously.
‘Mr. Holmes, it must be said at the outset that you have lately performed a service to your country such as few men have done for many years past. Thanks to you, we now have Dr. Gross and Herr Henschel where we want them.’
Holmes looked alarmed.
‘Not under arrest, I hope? I have had Sir John Fisher’s word on that.’
Swain shook his head.
‘No, sir. The First Sea Lord has kept his word. Indeed, you have given us an invaluable advantage in this. We are now reading their coded signals. But before we can take the matter further, we must identify the third member of their conspiracy, presumably at the Admiralty. When that is accomplished, we shall endeavor to turn their stratagem against them, rather than throw them into prison. Thanks to you, we have the means in our hands to save the lives of hundreds of our soldiers or sailors in the event of war, even to save our country from defeat.’
‘I am relieved to hear it,’ Holmes said, indifferent to such flattery.
‘And what have you done to identify the traitor in the Admiralty?’
‘Both Dr. Gross and Henschel are closely watched. From their method of procedure, it seems that Henschel probably knows nothing of the spy’s identity. It is possible that neither of them does. Henschel appears to be a mere technician who transmits whatever is given him. Each man works, as it were, in a watertight compartment. None of them, if he were caught, could betray any part of the conspiracy but his own.’
‘But you have connected their movements together?’
Swain sat back in his chair and folded his hands across his waistcoat.
‘We have had Dr. Gross under observation. He uses no telephone. He has sent two wires, both of which we have read. They were directed to the librarian at the British Museum, requesting certain books to be brought up from the stacks for Dr. Gross’s visit. He also receives a small amount of post, three communications in the past five weeks.’
‘You have opened those envelopes, Mr. Swain?’
‘We are aware of their contents, sir,’ said Swain evasively. ‘Apart from Henschel and Dr. Gross, there is the man whom I will call the naval spy. There appear to be twenty-four people at the Admiralty, from senior officers to junior clerks, who might have taken the design calculations of HMS
Renown
from the building in order to copy them. We have had them all under observation for some weeks and they have made no evident contact with either Dr. Gross or Mr. Henschel. Yet during that time, in the present international tension, the coded German signals have been transmitted almost nightly. We do not believe that Henschel can be transmitting from his rooms. Yet the signals are going out from somewhere near Sheerness, no doubt to a German naval vessel or trawler in the North Sea.’
At this point Swain took a notebook from his pocket and began to read a list of the information transmitted in the past few weeks.
‘Particulars of Armament:
Indefatigable
Class. Particulars of Anti-Torpedo Boat Guns, 4-inch and 6-inch. HMS
Princess Royal
: replacement of nickel steel, armour diagram. Comparison of Boiler Weights and Performance in HMS
Inflexible
, boiler by Yarrows, Ltd., and HMS
Indomitable
, boiler by Babcock & Wilson. I understand, gentlemen, that Yarrow boilers are lighter and would allow
Indomitable
’s six-inch armor to be increased to seven inches without affecting her speed.’
Alfred Swain paused, then added.
‘That is a sample of the technical information passing to our adversaries. More recently there have also been manoeuvre reports, gunnery ranges, torpedo matters, fire control, and signals. Last week, for the first time, there were answers to questions that Henschel must have received. Which parts of the fleet have been in the Firth of Forth since the beginning of May—the First and Eighth Destroyer Flotillas or any ships else? Have there been mobilizing tests of flotillas or coastal defences? What numbers of the Royal Fleet Reserve Class A reservists are called in for the yearly exercise?’ Swain paused and looked at us. ‘All these are details vital to the other side in any immediate preparations for war.’
Holmes crossed to the window, drew aside the net curtain, and looked down into the thin summer fog. It was possible to see across the street, and no doubt, though the barrel organ was still rattling out its tunes, he satisfied himself that the movements of our visitor were not under observation by our enemies.
‘Tell me about Dr. Gross, Mr. Swain.’
Swain looked a little uncomfortable.
‘There is little to tell, sir. He was an archaeologist as a younger man, with Schliemann at the discovery of Troy, and then deputy keeper of antiquities at the Royal Museum in Berlin. He has lived quietly as a retired gentleman in Beaumont Street for the past two years. He goes out either to the Ashmolean or to work in one of the libraries. He takes lunch at the Oxford Union Society, of which he is a member. That seems to be his only social contact. He retires early to his rooms until the next day. In the past five weeks he has visited London each Monday and stayed for one night at the Charing Cross Hotel. He leaves each morning after breakfast and walks up the Charing Cross Road to the British Museum.’
‘Who watches him?’
‘He works all day in the North Library, Mr. Holmes, where I have kept him company—at a distance. He speaks only to the assistants and leaves at five thirty. He dines early at an Italian café in Holborn, then walks back to the hotel by eight
P
.
M
. One of my colleagues is already dining at the café when he arrives. Dr. Gross speaks only to the waiter and returns direct to the hotel. Whoever the spy in the Admiralty may be, it seems he does not write to Dr. Gross, or speak to him, or communicate by telegram or telephone. We have watched the old man every minute, so far as we can. There appears to be no dead letter box except the hollow frame of the rack of camp stools in the Ashmolean Museum. Dr. Gross uses that only to leave the encoded messages for Henschel. It is possible that Henschel does not know the code and, though a member of the conspiracy, does not know precisely what the signals contain when he transmits them.’
Holmes sighed deeply.
‘I ask myself, if I were Dr. Gross, how would I manage it? Easily enough, I believe. There are so many ways! I daresay I would receive a letter at the Oxford Union Society. I understand it is run like a gentlemen’s club, where there is a very large green baize board next to the porter’s desk, crisscrossed with wire. Any letter through the post or a message by hand may be inserted there and left until the member collects it. The place is reserved to members only and you might keep observation outside for a month of Sundays without knowing what goes on inside.’
Swain looked a little embarrassed.
‘One of our plain-clothes officers has walked through that corridor and scanned the letter board every morning. There is never a letter for Dr. Gross.’
‘He may use another name and collect the letter even so.’
‘Mr. Holmes,’ said Swain quietly, ‘there are dozens, scores, of letters sent there every day. We cannot open them all, under every name, without giving the game away. In any case, he might as easily receive a letter at the Charing Cross Hotel, under any name.’
Holmes seemed to change tack.
‘Precisely. Then it must be a matter of observation—the most tedious of occupations. Yet it seems evident that Dr. Gross receives his information in London. Communication evidently does not take place between the time he leaves the hotel and the time he returns, unless something is slipped between the pages of a book on a British Museum shelf and he obtains it from there.’
‘I think not,’ said Swain quietly.
There the matter rested until three days later. At breakfast, Holmes said cheerfully, ‘I trust you have no engagements this evening, Watson?’
‘As it happens, I have not. Why?’
‘Because it is Monday and Dr. Gross, being a creature of habit, will spend the night at the Charing Cross Hotel.’
‘He may not.’
‘He will. I took the precaution of calling there yesterday and asking if a message might be left for him. It might, though I did not leave one. What shall we say? Eight o’clock precisely.’
‘How long for?’
‘My dear fellow, if I knew that, I should hardly need to go at all! All night if necessary, though I think that unlikely. It seems that the contacts Dr. Gross makes in London must take place during those hours at the hotel. I have also considered Swain’s suggestion that something is slipped into a volume at the British Museum. The reader inserts a message between the pages, hands the book in, the book goes back to the underground stocks. It is then ordered by another reader who retrieves the paper. I confess, I think that an unlikely method. There is the risk that it might be ordered by a third reader between those two or that the message between the pages might be noticed or even lost. Moreover, any investigation would instantly identify two members of the conspiracy rather than one. The Charing Cross Hotel seems altogether more probable.’
So it was that our cab carried us to the great lamplit space of Trafalgar Square and then into the Strand to the Charing Cross Hotel, next to the continental railway terminus. We made our way along soft carpets, down an avenue of gilt-columned mirrors and pillars of raspberry-coloured marble, to the First Class Lounge. The deep blue velvet arm chairs with a polished table next to each were reserved for those first-class passengers of the Southern Railway who awaited trains, at all hours of the day or night, to take them to the Channel ferries and on to Calais, Ostend, Paris, Berlin, or Milan.
Holmes selected a chair by the wall and pressed a small electric bell. A moment later it was answered by a ‘buttons,’ a youth in a page-boy’s tunic and trousers with a matching forage cap in chocolate brown. The brass buttons of the tunic had been polished until they almost dazzled the sight. At a second glance, I recognised his face as one of those young rascals who formed what Holmes called his Baker Street Irregulars and who had been our eyes and ears on so many occasions. In this case, the lad had grown out of childhood by a year or two but remained on what Holmes called his ‘little list’ of informants.
‘Been and gone, sir,’ he said, even before Holmes could ask the question.
‘Already?’
‘Yessir. Your gentleman that usually comes back from reading his books at eight o’clock must have missed his dinner tonight. He was back here at seven. Calls from his room at half past and gives me half a crown to fetch his package from the station cloakroom for him. He give me the cloakroom ticket and I come back with a little attaché case. Locked. Couldn’t say what was in it. Give me the other half a crown when I got back. A good night’s pickings, Mr. Holmes.’
‘A little attaché case,’ Holmes repeated thoughtfully. ‘Well done, Billy. Well done, indeed.’ His hand went into his pocket and a gold half-sovereign glinted as he discharged it into the waiting palm.
‘That will double what the other gentleman gave you. Now you may bring us two glasses of single malt and a jug of hot water.’
‘Not soda, Mr. Holmes?’
‘I am not accustomed to ruin a single malt with seltzer, Billy. Now, cut along.’ As soon as the lad was out of earshot, he turned to me. ‘Watson, we have them! Or we will have them by next Monday. Monday is the clue. A man who abstracts confidential papers on Friday evening knows that they will not be called for until Monday morning. He has the entire weekend to copy them. The maximum time and the minimum risk. On Monday morning he leaves the attaché case in the station cloakroom; inside it are the copies he has made. No doubt he then enters this hotel, seals the cloakroom ticket in an envelope, and leaves it as a message to be collected by Dr. Gross, on his arrival from Oxford later that day.’
‘By Jove,’ I said, half admiring these scoundrels, ‘and all that Dr. Gross must do on Monday evening is to give the boy the cloakroom ticket. The case is fetched for him.’
‘Just so. On Tuesday morning Dr. Gross gives the boy the empty case to deposit at the station cloakroom, and the boy brings back a new cloakroom ticket. Dr. Gross then puts the ticket in an envelope and posts it in the hotel letter box, so that it reaches his man by Wednesday, in time for the attaché case to be taken by this friend to his Admiralty office on Friday. Or he may summon a page to his rooms and send the lad to post it outside. The Special Branch would see nothing out of the ordinary. And so the game goes round.’
‘Indeed,’ I said, improving on this. ‘And when he sends the attaché case back to the cloakroom, it may not be empty. Gross would surely leave instructions in it, as to the documents to be copied that weekend. The Admiralty spy collects them on Wednesday evening at the latest, in ample time for this.’
‘Admirable, Watson! No doubt you were about to add that our Admiralty spy may also find in the case an envelope of banknotes, the wages of treachery.’
Billy returned with two glasses and the jug of hot water. Once he had gone, Holmes resumed.
‘Dr. Gross returns to Oxford on Tuesday and encodes the information, in time for Henschel’s visit to the Ashmolean on Saturday. And so the circle is closed. I should wager that none of the three men has ever seen either of the other two.’