A brief smile. An even swifter kiss, right there in the corridor, under Mrs Shaw's nose. "You, too." And then he was gone.

"Sacked! Do you hear me, Quinn? Pack up your things, this instant."

Mary started down the hal at a run. It was teatime.

Her Majesty would be in her private parlour, two storeys and half a Palace away. "Quinn! You're going the wrong way!"

She spared a glance for poor, overwrought, furious Mrs Shaw. "Yes, ma'am."

Her entry into Her Majesty's presence was a shade more circ.u.mspect: she entered the private parlour at a brisk walk, eyes lowered, and immediately prostrated herself in a deep curtsey.

Even so, Queen Victoria frowned and two burly footmen instantly caught hold of her, poised to march her from the royal presence. "This is highly irregular,"

said the Queen.

"I apologize for intruding, Your Majesty. I have done so only as a matter of national security." Mary raised her eyes although not her head and caught a glimpse of the Queen staring at her.

Honoria Dalrymple stood in a corner of the room, riveted by Mary's sudden appearance.

"Continue."

She nearly sighed with relief. "Your Majesty, the engineer engaged in repairing the tunnels beneath Buckingham Palace has discovered a grave danger. To preserve your safety, you must evacuate the Palace immediately."

The Queen stared at her for a ful ten seconds.

"We have not been informed of any danger by the Palace guards. What sort of danger?"

"Nitrocel ulose, which is also known as guncotton, Your Majesty. Sheets of cotton impregnated with nitric acid. They're highly unstable." Her training in the use of explosives had been brief but it was enough to know and fear the extreme danger of nitrocel ulose. Her heart squeezed painful y as she thought of James making his way back down into the tunnels. She couldn't afford to think further or imagine the worst.

"Impossible!" That choked utterance emanated from behind the Queen. Honoria Dalrymple's skin was ashen, her eyes wide and staring.

"I'm afraid not, Ma'am. Mr Easton, the engineer, is entirely reliable. He says this is a task for the army."

"Leave us," said Her Majesty.

Mary felt the footman pul ing on her shoulders.

"Please, Your Majesty, I a.s.sure you-"

"Not you," said the Queen. "We were addressing the others."

Honoria and the two footmen gaped at her. "But, Your Majesty, this is clearly..."

Even the footmen added their silent protest, dragging Mary a step closer to the door.

"Release this person and leave us now. Time is of the essence."

With reluctant, dazed steps, the three exited the room, so utterly startled that they failed to observe the rules of precedence.

The instant the door clicked behind them, Queen Victoria spoke again. "Your name?"

"Quinn, Ma'am. Mary Quinn."

"And how, Mary Quinn, are you so privileged as to know about threats to the empire before anybody else?"

She bowed her head. "I'm acquainted with the princ.i.p.al of Easton Engineering, Ma'am. He told me because it was the swiftest way. Your Majesty, I implore you to believe me."

"This is logical enough. But you must offer some form of proof of your reliable character: any sufficiently determined and resourceful mischief-maker could report such a tale. One could even heap some boxes in a disused sewer and pretend they contained explosives."

She was perfectly correct, of course and as reasonable and logical as Mary dared hope. "Your Majesty, I am the person recently engaged to resolve the matter of a string of petty thefts. I offer my employment as a character reference."

Queen Victoria's eyebrows shot up. "Indeed." Her unspoken thought was clear: not what I expected at all. But she soon ral ied. "I see. And if I were to ask for the emergency pa.s.sword?"

Mary tried not to grin. She'd never before had the opportunity to give the phrase that identified her to the client. "I would say 'Adrift in Zanzibar', Ma'am."

Her Majesty flashed a neat, vivid little smile that was promptly replaced by her usual gravitas. "In that case, we've no time to lose, Miss Quinn. Kindly ring that bel ."

Not for Queen Victoria panic and its attendant chaos. Within a quarter of an hour, the young princes and princesses and their attendants had been bundled into coaches for the short drive to Kensington Palace. The Queen had then summoned the most senior domestics and explained with admirable brevity the need for them to vacate the Palace immediately and without fuss. And she'd ordered the highest-ranking army officer in London to meet her at Kensington Palace. Now, the Queen of England and Empress of India stood outside, wrapped in a plain wool en overcoat, overseeing the departure of her staff of hundreds. Behind her, standing to almost military attention, was the Prince Consort.

"Your Majesty, with respect, time is short," said Mary.

Her Majesty nodded at the carriage that awaited her, not twenty yards off. It was an anonymous black coach, an irreproachable choice for discretion. "It is our responsibility to safeguard those in our employ."

"Yet your safety is of the utmost importance, both for your family and for the country."

The Queen gave her a sharp look. "And what sort of general would flee before the enemy, leaving his troops to scrabble their way to safety as best they could?"

"Please, Ma'am, at least stand away from the building. Every bit of distance is essential."

Queen Victoria agreed to this minor modification, but for Mary it was a nerve-racking wait while the last of the staff trickled from the Palace. They were an orderly crew although many, ignorant of the real reason for their departure, were distracted or fussy or general y reluctant. As they pa.s.sed beneath the Queen's gaze, however, each seemed suddenly tidied by an invisible hand: spines straighter, shoulders squarer, any whispers or giggles instantly quel ed. When at last they were al safely beyond the Palace gates, walking in neat procession through the parks like so many schoolchildren being given an outing, only then did the Queen permit her husband to hand her into the carriage.

From her perch on high, she looked down upon Mary. "Wel ? Aren't you coming, Miss Quinn?"

Mary shook her head. "It's most kind of you, Your Majesty, but I'm needed here."

The Queen elevated her eyebrows ever so slightly.

"Mr Easton said this was a task for the army."

"Yes, Ma'am. But until the army arrive, he'l need my help."

A long, hard look.

"Please, Ma'am your safety."

"She is right, Vicky," said Prince Albert.

"Very wel . We shal pray for your success, Miss Quinn."

Mary curtseyed very low. "Thank you, Your Majesty."

She waited only until the carriage was in motion.

Then, with one last look at the grey, drizzling world above ground, she hurried back into the Palace.

Twenty-nine.

Thursday afternoon Buckingham Palace sewers James stared at the crates of nitrocel ulose, wishing they were a hal ucination. This was entirely his fault.

Immediately after that bizarre midnight episode with the man with the etched-gla.s.s lantern, he ought to have sealed al sewer entrances and placed them under constant guard. Yet the idea of banning the flushers, of obstructing routine maintenance, had seemed excessive. He'd been reluctant to create panic where none was necessary, draw attention to a weakness that remained exposed. And this was the price for having been cavalier.

Now, he was responsible for the hysterical threat to, and possible destruction of, Buckingham Palace.

He knew precisely when the boxes had been moved in: at mid-morning, he'd been cal ed away from the site by a mysterious letter offering information about the midnight sewer-explorer. Like a fool, he'd succ.u.mbed to the ruse. Left the manhole under a watchman's supervision. And returned three hours later, none the wiser, to find the watchman had absconded. It had been annoying and worrisome.

But even then, he'd not expected the ful horror of what awaited him in that strange antechamber just off the main sewer.

It had taken time to work out what the boxes contained. One of nitrocel ulose's dangerous traits was its innocuous appearance. After al , it was merely cotton or wood fibres impregnated with nitric acid and left to dry. A crate ful of guncotton looked like so much harmless fabric unless one's suspicions were already flaring, as James's had been. He'd prised open each of the dozen boxes, dry-mouthed and sweaty-palmed the entire time. The slightest impact, a moment of clumsiness, and the whole tinderbox could have gone off.

The simplest way to neutralize the guncotton was to wet it again. He'd brought a pair of buckets with him and was busy fil ing them with rank water, hauling them up to the antechamber and careful y, nervously, pouring it into each crate. It was slow work: at this time of day, the sewers were down to a trickle and he had to travel downstream a few hundred yards in order to fil his buckets. The first time he'd tried to douse the guncotton, he'd held his breath, certain that it would ignite instead. But it hadn't.

He was filthy. Soaked to the skin. Shaking with nervous tension. He'd no idea whether Mary had been successful. He could hear constant, irregular rumbles that echoed up and down the tunnels the clatter of carriage-wheels on the cobblestones above, translated through layers of stone and earth and brick. But he couldn't hear activity from within the Palace, not even the scurrying of feet on flagstones. And yet, even as he listened, there came a new sound: light, tentative footsteps, coming from the Palace's access tunnel, just above this room.

He tensed. Set down his br.i.m.m.i.n.g buckets. He had the advantage, in some ways: he'd been down here longer, knew where the crates ended, could see general outlines even in the gloom. And this other person would have just descended a ladder.

But he was at a disadvantage, too: he didn't want to die down here in the sewers, and was intensely aware of the risks involved simply in being where he was. He forced himself to unclench his fists, to balance his weight lightly on the bal s of his feet. To be ready for anything.

The footsteps were careful, unhurried, yet steady.

From the click of the shoe soles on the ladder's metal rungs, the person wasn't wearing waterproofs and waders. Not a flusher, then. He waited, wondering if he'd positioned himself as wel as he'd thought: the crates were behind him, so that he might block the intruder's access to them. Perhaps he ought to have stayed behind them, for an opportunity to see the person before he showed himself. But it was too late.

In the near-darkness, he saw a pair of smal ish boots descending the last rungs, showing a clear three inches of ankle beneath a dark skirt, and he was instantly seized with panic and anger. He couldn't possibly recognize a pair of b.u.t.toned boots.

It was ridiculous. And yet, as the owner of the boots touched down with a soft thump and turned about, it seemed inevitable that it was she.

"I told you to evacuate with the rest of the staff," he snapped.

She dusted off her hands. "So you did. And good afternoon, by the way."

"It's not, actual y. Get out. Go."

And yet she came towards him, eyeing the looming stack of crates with respect. "That's an enormous quant.i.ty of nitrocel ulose."

"Enough to blow us up a hundred times over," he agreed. "Which is why you're leaving this instant."

"Only if you come with me." She held out her hand.

He stared at it, tempted. "Someone's got to guard the crates until the army can dispose of them."

"That's what I thought. I've come to help."

He squinted at the ladder and its chute, wondering if he had enough clearance simply to throw her over his shoulder and carry her up by force.

"It's no good," she said in a sweet voice. "I'd only struggle. And that would leave the crates unguarded."

Not for the first time, he was tempted to shake her.

Instead, he drew a deep breath. Contained his anger. "Mary. Is there nothing I can say or do to induce you to leave?"

"No. You need help. Now tel me what to do." She was already rol ing her sleeves, turning up her skirts to knee height for freer movement.

He sighed. Gritted his teeth. Then said, "We'l make a relay: I'l fil the buckets and pa.s.s them to you; you soak the guncotton and return the buckets at the midpoint."

"Very good."

"Seems a long way from good to me."

She rol ed her eyes. "Al right: very sensible."

She was irresistible. He leaned down and planted the swiftest of kisses on her lips. "I do love a sensible girl." And then he turned away, bucket in hand, before she could think of a riposte.

Thirty.

Once they'd settled into a rhythm, Mary found it difficult to believe in their imminent danger. It was hard graft, of course dirty, cold, slippery, splashy but the guncotton looked so harmless. Nevertheless, they laboured on. After nearly half an hour, they'd fetched enough water to soak through two-thirds of the crates. The emergency would soon be averted.

And yet Mary remained troubled by the use of a substance so volatile.

When she next met James to exchange buckets, empty for ful , she said, "Doesn't it seem strange to you, the use of nitrocel ulose?"

"How d'you mean?" He sounded distracted and squinted down the tunnel at some invisible end point.

"The whole scheme seems oddly uncalculated ...

more like a general, irrational gesture than a specific threat to the Crown."

"I'd say that planting any type of explosive beneath Buckingham Palace is irrational."