I watched my partner drive away before I turned and entered the castle. The black raven on the coat of arms above the main gate seemed to greet me like an old friend. I still remembered the day a few months ago when I passed beneath this archway for the first time—and suspected the stylised bird was mocking me. Now, the glint in his eye seemed more like genuine humour than scorn.

Marie and Frédéric, the French couple I had met at breakfast, sat in wicker chairs in the courtyard café and braved the cool afternoon air, studying their travel guidebook. I waved, and they greeted me back. These days, Corbières Castle served as a backpackers' hostel and was well-frequented thanks to its growing reputation as a haunted place.

I picked up lunch in the kitchen and retreated to the library, the corner room on the first floor that held a vast collection of books, from worn paperbacks to ancient leatherback tomes covering everything from local plant lore to science fiction. Several former owners of the castle had contributed to the collection and Lou loved it enough to keep it open to the public. But most visitors spent little time in the room. They came for outdoor activities or, for the last few months, to get to stay in a haunted place.

So, the library doubled as an informal headquarter for Ghost Guard Sárl, the company Matt and I had launched after the success when we ridded the Corbières Castle of a flock of ectoplasmic ravens. Our third partner, Theo, had turned out to be a ghost himself—and connected to the case. It took us a while to unite him with his lost wife and child. But when we did, the annoying birds had disappeared with them in the rising floods of the lake. This initial success and Lou's gratitude had given Matt and me the courage and the financial means to start our own business.

Since then, we had solved a few minor cases of paranormal activity in the region. I chuckled when I remembered the case of the black ghost dog howling in an empty parking lot at midnight. The animal turned out to be very much alive but shy, plagued by fleas, and in need of a caring home. The trickiest part was to find a caring owner for the poor bugger. Matt convinced the neighbour who had engaged us to solve the case to the Labrador. When we left, both the lady and the dog seemed happy with the new arrangement. She even sent us a selfie of her and her cleaned up pet to thank us.

In the company of Mister Mortimer, the black cat I suspected of being Corbières Castle's true master, I sifted through our business mail and answered a few requests, hoping for a serious job offer. But the only thing I found were advertisements and someone offering to do ouija seances for our company. I wrote a polite answer, aware most so-called mediums were fake. The real ones would know better than to offer their services to colleagues they didn't know.

When the daylight faded to dusk, Louis Connelly, the current owner of the castle and manager of the hostel, joined me. He pecked me on the cheek and grinned when he saw I still wore my new hiking boots. "Seems they didn't leave your feet all blistered after all. When did you come back?"

"Around two, I guess, and yes, I decided I like them. They are comfy." I wriggled my toes. They didn't feel cramped at all.

"Then we should put the boots to the test soon, if the weather permits. Do you think Matt is still happy to stand in for me at the hostel for a few days?"

"Sure, I think he looks forward to play master of the castle. And as our potential case turned out to be a major fail, we can schedule the outing whenever you like."

He reached out a hand to help me up. "Wonderful, well, not the fail, but the part about Matt and the hike. I'll start looking for accommodations. Like some dinner?"

My rumbling stomach agreed. The conversation only turned back to my visit in the town of Avenches when we drank coffee in Lou's living room. A fire in the wood stove chased the autumn chill from this sanctuary of medieval architecture, comfortable furniture and modern art. Lou leaned back in his favourite armchair. "You still didn't tell me about your encounter with the spectre haunting Aventicum."

"That was just a flimsy ghost of the past, if I dare say. Not of the paranormal kind. Matt's ex threw a fit and forbade us to stay on the site. But while we were there, the place seemed clean, no manifestations, unlike..." Belatedly, I remembered the visit of the bird in front of the depot and snapped my fingers. "I forgot about the newspaper and the Raven."

When I explained about my clash with the ghost bird, Lou frowned. "The castle wasn't visited by ectoplasmic birds in months. I thought they disappeared when the lake level returned to normal and swallowed the haunted cottage by the shore with Theo's ghost and his family."

"So was I, and I doubt it's the same bird I've seen. Yet there was a huge black raven at the museum's depot today, and he brought this newspaper to my attention." I retrieved the paper from my backpack and spread it on the coffee table. "Here—October 10th, 1989. I wonder what happened back then that warrants the intervention of an ancient one."

Lou ran a finger over the faded headline. "It's a local paper. Are you sure this isn't just a coincidence or a stupid prank?"

I shrugged. Sometimes, I wasn't even sure about my gift myself, so how should I explain it to someone who had no special sensitivity for ghosts? I searched for adequate words when a tingle in my wrist announced company. An unnatural chill filled the air, and I glanced around, trying to spot the visitor.

For a moment, the bright red and blue colours of an oversized cubist painting faded and the translucent form of a medieval knight floated through the artwork into the room. The flickering firelight reflected on thousands of tiny links in the chain mail of his hauberk and chausses. The raven on his off-white surcoat, the coat-of-arms of Corbieres, seemed to blink at me.

Mister Mortimer hissed and retreated to a windowsill. Like most cats, he wasn't fond of ghosts.

The semi-transparent figure of the knight ignored the feline and the room's furniture and stopped in the middle of the coffee table to flourish his purple velvet cape in an elegant bow from the waist. "What a pleasure to meet you both in great health, Lady Sandrine, Master Louis."

"Sir Guillaume, happy to see you, too. How's afterlife?" I didn't have to fake my joy. The ghost of Guillaume de Corbières, the castle's founder, was always good company, and today I had a few urgent questions for our resident expert in paranormal affairs.

Guillaume chuckled, his wobbling belly jingling the links of his mail shirt. "Afterlife is marvellous. Thanks for asking, my lady. Although that young French couple visiting the spa might be of a different opinion."

I raised my brows. "You had an encounter with Marie and Fred?"

Lou sighed. "Don't tell me you spooked our guests."

"My apologies. I enjoyed the bubbly pink stuff in the whirlpool when they intruded. They were so engrossed with each other they didn't see me before they were almost on top of me."

I imagined the faces of the lovebirds when they found the pool occupied by a middle-aged gentleman in full armour, covered in pink lavender bubbles—and burst out laughing. Lou pulled a face at first, but joined me a moment later. "Right, I'll better check on them. Don't want to risk any guest having a cardiac arrest."

He blew me a kiss, shook his head in mock desperation, and left. Guillaume glanced after him. "Is he angry?"

"No, I don't think so. But being the manager of a haunted hostel can be quite demanding."

My explanation must have carried more of my hidden emotions than I intended. Sir Guillaume's features softened. "I'm sorry I interrupted your private moment, my dear."

"It's fine. We are planning a holiday and hope to enjoy a few days away from the castle and Lou's manager duties." Suddenly, I wished we could go on that hike tomorrow.

The ghost pointed at the newspaper he was standing in. "Is this part of the holiday planning?"

"No, that's another weird conundrum of the paranormal kind to solve. The Raven pointed it out to me, and I have to figure out why."

"A riddle." Sir Guillaume's eyes lit up like glowing coals. If I hadn't known him well, I'd been frightened by the dramatic effect. "What is it about?"

"I don't know, but if you step out of it, we can try to find out together."

The ghost didn't waste time. After centuries spent hanging around Corbières castle, Guillaume was keen on anything that promised entertainment. This made him an irreplaceable asset to the Ghost Guard. He watched over my shoulder as I flattened the newspaper and scanned the content of the brittle first page. It didn't take long to spot the important headline in the column to the right.

"Here, this must be it. Archaeological excavation in Roman Avenches—spectacular finds in the En Chaplix cemetery. Read more on page 15."