A larger shadow scuttled past and I caught my breath, but it was only Kip.

"Boo," said Adrian, by my shoulder.

I called him something rather rude. Beside me, Fabia stopped walking.

"Look, this is far enough, surely," she said, hunching into her jacket. "Davy, isn't this far enough?"

He agreed that it probably was. We'd come roughly a quarter of the way across the field, fully one hundred yards from the house. There was little chance of Peter hearing us from here, unless we shouted.

"Perfect night for ghost-spotting," said Adrian, as he flung himself full length upon the grass. "Pass me my flask, will you, Verity love? Or have you drained it already?''

"I only had a taste." I rummaged for the leather-covered bottle. "Vile stuff, that."

"Yes, well, Russian wine is not exactly noted for its subtlety," he told me, taking a healthy swig.

Jeannie smiled. "A gift from Brian, was it?"

"Not exactly a gift. I paid him ten pounds for the case, I think." He rolled his head sideways to grin at her. "Not that I recall the deal too clearly. We'd already downed a bottle between us by then." He offered the flask around, but Fabia was the only one brave enough to accept. She gave a little choking cough and passed it back.

"God." She grimaced. "That is terrible." Pushing the tumbled hair out of her eyes, she drew her knees up and rested her chin on her hands. "I was just thinking, we don't really know that this ghost is roaming about at night, do we? I mean, Robbie's only seen him in the daytime."

"That's true," said Jeannie, sagely. "But it does seem rather a safe bet..."

"Ghosts always prowl at midnight," Adrian cut in, with smooth authority. "Didn't you watch films at all, when you were growing up?"

"He'll be here," Wally said. His voice was simple, calmly knowing. “He walks by night as well as by day. Just ye ask yon dog."

I looked to where the collie lay sprawled out upon the grass, head up, ears perked, and I remembered it would probably be Wally who took Kip out late at night, when Robbie was in bed. Perhaps Wally had seen what I had seen—the collie dancing at the heels of an invisible companion, begging to be patted, broad tail waving. It was a sight one didn't soon forget.

Something, some animal, scuttled through the rough grass and Kip gave an eager whine, but Wally's hand reached out to keep the collie still. My own gaze moved from the waiting dog to the old man's moonlit profile, and I rubbed my leg with a thoughtful hand. "Do you believe in ghosts, Wally?"

His shrug was noncommittal. "Depends."

"You're all daft," Adrian pronounced his judgment lazily, leaning back on his elbows. "A ghost is merely a projection of a less than stable mind."

David's voice came quietly. "Is that a fact?"

"It is. Christ, I've been working here two months now, puttering about this field with my equipment, and I think I would have noticed anything out of the ordi—"

"Salve,'' Robbie said.

He was sitting close beside me, near my feet, and the sudden sound of his small voice made me jump. Just as suddenly, he turned around and showed me a brilliant grin. "Hey, it works!"

My throat worked for a moment before the words found their way out. "That's wonderful, Robbie. Where is he?"

I wouldn't have believed my voice could sound so calm, when I was anything but calm inside. My nerves were thrashing wildly, like a netted bird, and my heartbeat pulsed a hard and rapid rhythm in my throat. It was one thing to come up with the idea of talking to the Sentinel, I thought, but my bravado shriveled with the knowledge that our ghost was standing right in front of us.

"Right there," said Robbie, pointing to the vacant air.

David slid the few feet down the slope to join us, coming to an abrupt stop directly behind me and steadying himself with a hand on my shoulder. I could feel the warmth of him through the thick folds of my jumper, but I don't believe he even noticed the touch. Above my head, he watched the darkness steadily. "Say 'salve custos,' Robbie," he instructed.

"What's custos?"

"Sentinel."

We were all silent now, leaning slightly forward in anticipation as Robbie dutifully repeated the words. I counted my heartbeats ... one ... two ... before the boy turned around a second time, his eyes going over my head, seeking David's. "He's not saying anything, but he's smiling. He's looking at you, now."

"Is he, by God?" David frowned a moment at the nothingness, then raising his voice he explained in perfect Latin that we couldn't see or hear our long-dead visitor; he would have to talk through Robbie.

"Now, Robbie," David murmured, "if he says anything, if he makes a sound, you repeat it, all right? Like a parrot."

"All right."

David nudged my shoulder. "Go on, then," he invited me. "It's your party. You ask the first question."

Fabia, who'd been holding her breath all this time, let it out again in a swift, expectant rush. "Ask him," she hissed, "if he knows he's a ghost."

Adrian ventured dryly that, after walking the same field for several hundred years, a person must surely begin to suspect...

Turning, I sent him a withering look. "Will you be serious?"

Adrian rolled his eyes. "Oh, right. You're talking to thin air, and I'm meant to be serious."