"I'll be careful," he whispered throatily. "And when the mystery is solved, shall I return to tell you about it?"

"Yes. Come back, please, Captain Burton."

It was midday, but London, buried in the heart of the congealing fog, was deprived of light. It tried to generate its own-gas lamps and windows blazed into the murk, but their fierce illumination was immediately crushed and reduced to vague patches of yellow, orange, and red. Between them, the vast and sickening gloom writhed like a living entity, consuming all.

"That you, guv'nor?" came a gruff voice from above.

"Yes, Mr. Penniforth. You're still breathing?"

"Aye. Been 'avin' a smoke o' me pipe. There ain't nuffink like a whiff o' Latakia for fumigatin' the bellows! Get yourself comfy while I light the bull's-eyes. An' call me Monty."

Burton climbed into the hansom. "Bellows?" he grunted. "I should think your lungs are more like a couple of turbines if they can deal with that fog and Latakia! Take me to Scotland Yard, would you?"

"Right ho. Half a mo', sir!"

While his passenger settled, Penniforth climbed down from the box, struck a lucifer, and put the match to the lamps hanging from the front of the engine, and the front and rear of the cabin. He then hoisted himself back up, wrapped his scarf around the lower half of his face, straightened his goggles, gave the peak of his cap a tug, and took hold of the steering bars.

The machine coughed and spluttered and belched smoke into the already laden atmosphere. It lurched away from the curb, pulling the cab behind it.

"Hoff we go, into the great unknown!" muttered Penniforth.

As he carefully steered the machine out of Mornington Crescent and into Hampstead Road, there came a mighty crash and tinkling of broken glass from somewhere far to the left.

"Watch out!" he exclaimed softly. "You don't want to be drivin' into a shop window, do you! Irresponsible, I calls it, bein' in charge of a vehicle in these 'ere weather conditions!"

By the time the hansom cab reached Tottenham Court Road, the "blacks" were falling: coal dust coalescing with particles of ice in the upper layers of fog before drifting to the ground like black snowflakes. It was an ugly sight.

Penniforth pushed on, guided more by instinct and his incredible knowledge of the city's geography than by his eyes. Even so, he steered down the wrong road on more than one occasion.

The steam-horse gurgled and popped.

"Don't you start complainin'!" the cabbie advised it. "You're the one wiv a nice hot boiler! It's cold enough up here to freeze the whatsits off a thingummybob!"

The engine emitted a whistling sigh.

"Oh, it's like that, is it? Feelin' discontentified, are you?"

It hissed and grumbled.

"Why don't you just watch where you're a-going and stop botherin' me wiv the benny-fits of your wisdom?"

It rattled and clanged over a bump in the road.

"Yup, that's it, of girl! Giddy up! Over the hurdles!"

The hansom panted through Leicester Square and on down Charing Cross Road, passing the antiquarian bookshops-whose volumes were now both obscure and obscured-and continuing on to Trafalgar Square, where Monty had to carefully steer around an overturned fruit wagon and the dead horse that had collapsed in its harness. Apples squished under the hansom's wheels and were ground into the cobbles; the resultant mush was quickly blackening with falling soot.

Along Whitehall the engine chugged, then left into Great Scotland Yard, until, outside the grim old edifice of the police headquarters-a looming shadow in the darkness-Penniforth brought it to a standstill.

"There you go, guv'nor!" he called, knocking on the roof.

Sir Richard Francis Burton disembarked and tossed a couple of coins up to the driver.

"Toddle off for a pie and some ale, Monty. You deserve it. If you get back here in an hour, I'll have another fare for you."

"That's right gen'rous of you, guv'nor. You can rely on me; I'll be 'ere waitin' when you're ready."

"Good man!"

Burton entered Scotland Yard. A valet stepped forward and took his coat, hat, and cane, shaking the soot from them onto the already grimy floor.

Burton crossed to the front desk. A small plaque on it read: J. D. Pepperwick-Clerk. He addressed the man to whom it referred.

"Is Detective Inspector Trounce available? I'd like to speak with him, if possible."

"Your name, sir?"

"Sir Richard Francis Burton."

The clerk, a gaunt fellow with thick spectacles, a red nose, and a straggly moustache, looked surprised.

"Not the explorer chappie, surely?"

"The very same."

"Good gracious! Do you want to talk to the inspector about yesterday's shooting?"

"Perhaps. Would you take a look at this?"

Burton held out his authorisation. The clerk took it, unfolded it, saw the signature, and read the text above it with meticulous care, dwelling on each separate word.

"I say!" he finally exclaimed. "You're an important fellow!"

"So-?" said Burton slowly, suggestively inclining his head and raising his eyebrows.

The clerk got the message. "So I'll call Detective Inspector Trounce-on the double!"

He saluted smartly and turned to a contrivance affixed to the wall behind him. It was a large, flat brass panel which somewhat resembled a honeycomb, divided as it was into rows of small hexagonal compartments. Into these, snug in circular fittings, there were clipped round, domed lids with looped handles. A name was engraved onto each one.

The clerk reached for the lid marked "D. I. Trounce" and pulled it from the frame. It came away trailing a long segmented tube behind it. He twisted open the lid and blew into the tube. Burton knew that at the other end a little valve was popping out of an identical lid and emitting a whistle. A moment later a tinny voice came from the tube: "Yes? What is it?"

Holding its end to his mouth, the clerk spoke into it. Though his voice was muffled, Burton heard him say: "Sir Richard Burton, the Africa chap, is here to see you, sir. He has, um, special authorisation. Says he wants to talk to you about the shooting of John Speke at Bath yesterday."

He transferred the tube to his ear and listened, then put it back to his mouth and said, "Yes, sir."

He replaced the lid, lifting it back to its compartment, the tube automatically snaking in before it.

He smiled at Burton. "The inspector will see you straightaway. Second floor, office number nineteen. The stairs are through that door there, sir," he advised, pointing to the left.

Burton nodded and made for the doors, pushed through them, and climbed the stairs. They were wooden and needed brushing. He came to the second floor and moved along a panelled corridor, looking at the many closed doors. The sound of a woman weeping came from behind one.

About halfway down the passage he found number nineteen and knocked upon it.

"Come!" barked a voice from within.

Burton entered and found himself in a medium-sized, high-ceilinged, square, and shadowy room. Its dark corners lay behind a thin veil of blue cigar smoke. There was a very tall, narrow window in the opposite wall, a fireplace with quietly crackling logs in its hearth to his right, and a row of large filing cabinets lining the wall to his left. A red and threadbare rug covered the centre of the floor, a hatstand supported a battered bowler and dusty overcoat by the door, and a big portrait of Sir Robert Peel hung over the fireplace. Gas lamps flickered dimly in the alcoves to either side of the chimney breast. A lit candle wavered on the heavy desk beneath the window. It cast an orange light over the left side of Detective Inspector Trounce's face.