William leaned against the wall as a nurse walked by. “The thing is, we’ve been following the top brass around. Top secret, it is, but the Cabinet War Rooms are beneath the Government Offices on Great George Street. That’s where they control the whole war from, you know. The prime minister’s there for most of the day.”

Flossie covered her mouth with her keyed hand, shocked. “And that’s where the German officer was seen?”

“Heading for the War Rooms, yes. Seemed like he knew where he was going, too.”

“Which means he’s known where they are for —”

“We don’t know how long, miss, but longer than we have. Worse still, the men got a good look at him — at his uniform and his medals.” He paused to whistle. “That one would have had the ear of Hitler, that’s for sure.”

It was as Flossie had feared but had been too scared even to give thought to. To put a name to. Because she wasn’t sure how it could be possible. Or what it might truly mean.

The German officer was a spy.

“You just missed our Turnkey. The thing is, the men and I were talking to him. The German officer can’t still get information to him, can he, miss? To Hitler, I mean. We asked our Turnkey, and he said no. We wanted to ask you as well.”

“I don’t think he’d be able to,” Flossie said. But she was beginning to become very afraid that she might be wrong about that. What if he’d found a way? A way to bridge the gap between the living and twilight worlds. It wasn’t supposed to be possible — every person in the twilight world knew that. There was no way for them to communicate with the living, and no way for the living to communicate with them. Flossie remembered something. “And the word that the girl mentioned? The Ahnenerbe?”

“One of the men, Leo, had a German grandmother so he speaks a bit of German, and he said the word means a legacy. You know, something inherited from the people who came before you.”

Flossie considered this. “That doesn’t make sense. The girl told me he was ‘part of the Ahnenerbe.’ As if it were some sort of a group.”

“We’ll keep asking around. Right now it might be best to return to the War Rooms. See what’s going on there.”

Flossie held out her keyed hand toward William. “You’re right. Just tell me where to go.”

William directed Flossie to take them to the corner of Horse Guards Road, Great George Street, and Birdcage Walk. When she opened her eyes, the first thing she saw was a large wall of sandbags directly in front of them.

“Get down!” Someone tugged on her dress, and both she and William were unceremoniously pulled to the ground. They landed cross-legged, their backs against the sandbags.

“Sorry, miss,” said a Chelsea Pensioner she hadn’t met before, “we don’t want him to see us. He was close by not long ago, lurking around Number Ten. We think the prime minister’s on the move.”

Flossie slumped against the sandbags. Things were only getting worse. Now the German officer was at the prime minister’s official residence at 10 Downing Street!

Another Chelsea Pensioner flew around the corner of the long wall of sandbags and rushed over to them, his coat flapping. “The German officer’s down there now. In the War Rooms. They’re all there — Churchill and all. There’ll be a meeting soon, I’d say. But there’s more. That thing he’s got? It’s not a crystal ball. It’s some kind of a skull.”

“A skull?” William and Flossie said at the same time.

“Not only that, but he’s talking to it. Arguing with it in German. The man’s stark raving mad! Leo’s down there listening in, translating what he can. And believe you me, you’re not going to like what he’s overheard.”

Flossie and the men walked past the sandbags and barbed wire and down to the entrance to the bunker. Two Royal Marines stood at attention, guarding the open entrance — a wooden door. The men had helmets on their heads and rifles by their sides.

Taking the lead, Flossie slipped past the marines and through the open doorway. They proceeded until another Chelsea Pensioner came into sight. He had been peering into a different corridor, and now he beckoned them toward him, at the same time holding a finger to his lips, warning them to be quiet.

Obviously the German officer was close by.

The foursome continued along soundlessly. When they reached the other Chelsea Pensioner, the men shuffled Flossie forward so she was at the front of the group. William followed her.

Flossie took a peek herself. A long corridor presented itself. It was rather like a rabbit warren down here — doors leading off either side of the passageway. Some of the doors were open, and she could see that the rooms inside were tiny and almost cell-like. A woman in a plain blue dress, a knitted cardigan, and immaculate red lipstick passed by in a hurry.

One of the men tapped Flossie on the shoulder and pointed around the corner to the left.

“Down there,” he whispered to William and Flossie. “He’s in that room. Leo’s in the opposite room across the hall, listening in.”

“We’ll go down there,” William said.

Flossie followed him, gripping her key so it wouldn’t clank on its iron ring and alert the German officer to her presence. Just as the Chelsea Pensioner had said, there was already a man in the small room — Leo.

William and Flossie crowded in beside him.

“What’s going on?” William whispered.

“He seems to have quieted down,” Leo said, his voice low. “But he was ranting and raving before, shouting at that skull of his. Strange thing, that. Doesn’t seem like it belongs in our world, does it? What do you think he’s doing with it? That doesn’t come standard issue with —”

Everyone jumped as a voice shouted in German. Flossie listened in as the foreign words rose and fell. A pause. Then more words. Then another pause. It really was as if he were arguing with someone.

“What’s he saying?” she asked Leo.

“Mostly the same thing,” he said, concerned. “That he’ll be back, that it will all be over soon, that his actions will mean a quick and easy end to the war. Before he went into that room there, he was in the map room. He read out a whole lot of coordinates. Almost like he was reading them to someone, or dictating them.”

There was no doubting it now. He was gathering information. He truly was a spy.

“Can I go and see what he’s doing?” she asked Leo.

“It should be all right. His back is to the door.”

“Keep low,” William warned her.

Getting on her hands and knees, Flossie crossed the corridor swiftly. She eased onto her stomach and peeked around the edge of the doorway.

The German officer sat in a tiny room with not much more than a desk, a wooden chair, a shiny black telephone, and a green glass banker’s lamp. His uniformed back to her, he shifted in the chair, and Flossie flinched. Instead of turning, though, he leaned forward and began to speak. Flossie lifted her head to see what held his attention.

It was just as she’d been told. It was a glass skull he was speaking to. She hadn’t been able to see its shape properly up on the top of St. Paul’s, but she saw it now — the round, smooth top, the hollowed-out eyes, the narrowing of the jaw. He had his hand upon it as he talked, and every so often he leaned in farther, almost crooning to it. Her eyes locked onto it, mesmerized. She’d never seen anything so bright in the twilight world before.

Some movement down the corridor made Flossie draw her head back. Uniformed men of the living world were coming. She crossed back to the room with William and Leo, hiding herself away.

As the men passed by, Flossie caught snippets of their conversation. They were talking about a meeting.

“They mentioned that before. There’s going to be a meeting very soon. In the Cabinet Room. With the prime minister,” Leo said.

“Tell the young lady what you just told me,” William said to Leo, his expression grave.

Leo’s brow furrowed. “I’m sorry, miss, my German’s not that good. Before you got here, just after he’d been in the map room, he did mention something else.”

“What?” Flossie’s hand clenched tight around its iron ring. “What did he say?”

“I didn’t catch all of it, but he’d been talking about an invasion. And then, a while after that, he said something about Highgate Cemetery. About Highgate and about Kensal Green, too.”