Chapter Five.

The Diurnal Vault, Arx Angelicum, Baal.

Even after decades of serving as a member of the Blood Angels Librarius, Mariah never failed to hesitate at the threshold of the Diurnal Vault. At Mephiston's side she had crossed the Imperium, seeing sights that would fracture a mortal mind. But it was here, in the fortress-monastery of her own chapter, that Mariah felt most humbled. The vault was her and Mephiston's private library and it was built on such a grand, visionary scale that it resembled a work of nature rather than man. Its cavernous size was impossible by any normal laws of physics. Far larger than the wider Librarium that contained it and it was dominated by a statue of Sanguinius that would have dwarfed a cathedrum. Solar lights burned from the statues chest, filling the hall with shifts of glittering dust motes and flashing on three faceted monoliths that hovered above the angel's outstretched hand. Up on entering the vault, Mariah shrugged off the constraints of gravity and drifted up past the contours of the statue, following Mephiston as he headed towards the three enormous crystals. After leaving the Octocalvariae, Mephiston had ordered Rhacelus and Antros to ready his ship the Blood Oath and muster the strike force Commander Dante had promised them. Mariah had intended to return to her own chambers and prepare for the journey, but Mephiston had ordered her to assist in his search for more information about the entity known as Dromlach.

"Do you believe what the creature said?" asked Mariah as they glided towards the three gemstones. "That there is a galactic serpent called Dromlach?"

Mephiston shook his head. "I'm sure there are far worse things spewing from the Great Rift, but if this particular horror had been around for as long as the creature claimed we would have heard of it before now."

They Reached the first of the gemstones and Mariah struggled to take in the scale of it. It resembled a polished ruby but a ruby the size of a troop transport and surrounded by swarms of winged servitors and servo-skulls. Mephiston led her through a glit-edged aperture in its wall and gravity returned, dropping the two Librarians onto a mosaicked, rut-strewn floor. Blood thralls rushed towards them but Mephiston waved them away, striding through the antechambers into a larger, octagonal room. Its walls were lined with bookcases that reached hundreds of feet up to a distant, vaulted ceiling. There was a pleasing hum of scholarly work as servitors cradled the books in their servo-arms and transcribed information from mouldering pages to datacreeds that scrolled endlessly from their chests. There were mortals present too, scholiasts and rubricators, hunched over desks and clinging to ladders as they catalogued and restored.

Mephiston ignored all of it, striding across age-worn rugs to an alcove on the far side of the chamber.

"But you seemed pleased," said Mariah hurrying after him. "When the creature mentioned the Dromlach I saw your eyes light up." They entered the alcove and Mephiston dismissed the group of blood thralls gathered at its shelves. He waved Mariah to a table, indicating that she should sit on a specific chair, and then began placing texts in front of her – everything from mass-produced pamphlets to hefty glit-edged folios.

"The word Dromlach is significant," said Mephiston, sitting opposite Mariah and opening a book. "But it does not mean what the Octocalvariae says. Whatever cruel trick it thinks it has played on me has no bearing on reality."

He paused and glanced out of the alcove, back into the main chamber. "Oraculist," he said. He spoke the word quietly, but Mariah felt the psychic kick that projected it across the hall. Mephiston nodded to the books in front of Mariah. "Find every mention of a Dromlach or the Dromlach and find a connection."

Mariah realised that, rather than navigational treaties and star charts, Mephiston had given her books on comparative religion. She shrugged and did as instructed, scouring indices and contents pages and scribbling notes on a sheaf of paper.

She lost herself in the work, cross referencing and re reading, looking for anything that linked the different descriptions of Dromlach. She quickly spotted a recurring theme. In every culture that worshipped or feared Dromlach, there was a belief that it was a living portal – a rout from the real world to the afterlife. But beyond that, he could find nothing that would help them cross the Great Rift.

There was a flutter of mechanical wings as Mephiston's servitor arrived carrying the metal salver. Mephiston took the Ephemeris and placed it on the floor next to the marble table, leaning over it and tracing the design with his finger.

They passed several hours this way, with Mephiston poring over the books and occasionally using a stylus to inscribe a new note on the Emphemeris.

"Have you found any Imperial records that mention Dromlach?" asked Mephiston.

Mariah looked up with a frown, about to ask Mephiston why he needed help recalling facts. Mephiston knew every line in his Librarium.

"Some of these texts are new," said Mephiston sensing her question through the Nexus Link. "I only have second-hand knowledge of them."

Mariah nodded and picked up one of the smaller books, holding it out to the Chief Librarian. "There was an explorator fleet led by a Magos Stormgren. They used the word Dromlach in their final communiques."

"Final?"

Mariah took the book back and flicked through it until she found the relevant pages. She pointed to a line of text. "The fleet went missing. It vanished in..." She frowned. "Can that date be right? It predates the Imperium."

"Of course. The priests of Mars have been playing the galaxy since before the days of the Imperium. Rhacelus would cuff you for asking that question. Where did the fleet go missing."

"It says they were last seen entering a region know as the Cronium Gulf." Mariah shrugged. "I suppose that name might no longer be in use."

Mephiston stared at Mariah.

"My Lord?" said Mariah.

Mephiston did not seem to hear. He was no longer looking at Mariah but through her. His gaunt, severe features had slackened and for a moment he looked as cadaverous as he did before the tech-priests remade him.

After a long, discomforting minute. Mephiston's eyes refocused on Mariah. "I see," he said, his voice slipping back into the heavy accent he used when focused on a blood ritual. "We are getting somewhere."

"Are we?"

Mephiston nodded and lifted the Emphemeris off the floor and up onto the table. He pointed out several of the glyphs on its surface. "There are only a few mentions of Dromlach on here, but the Cronium Gulf crops up many times."

He stood up and strode quickly back into the main part of the Librarium with Mariah racing after him. Mephiston grabbed more books and returned with them to the alcove.

"Look for any mention of the Cronium Gulf," he said.

In a few minutes a fascinating picture had appeared. Imperial fleets had mentioned the Cronium Gulf several times and each time they did, it was the last message they sent.

"Ships enter that gulf and do not reappear," said Mephiston, scoring more notes into his salver.

"It's been happening since before the birth of the imperium," replied Mariah, her pulse quickening.

"And look here," Mephiston held out a page for Mariah to study. "A xenos fleet vanished in the same location and they referred to gods called the dromas who guard the religion."

As they read further, it became clear that every civilisation near the Cronium Golf lived in fear of a creature called Drumus or Dromos or something similar.

"Myths like these don't always come about by accident," said Mephiston. "Perhaps someone or something wishes to keep people away from the Cronium Gulf." He peered at his notes. "The monster names are a smokescreen. There is something important there that causes fleets to vanish." He lent back in his chair, drumming his fingers on the table. "We have our destination, Mariah. This anomaly must be our route across the Great Rift. As soon as Rhacelus and Antros return with news of the Blood Oath we will depart for the Cronium Gulf."

But, my Lord, all of this is based on the words of the creature. It gave you the name Dromlach so it must have meant for you to find out about this gulf." she shook her head. "If a Chaos-worshipping xenos wants us to go there, how can it be in our best interests?"

Mephiston waved a dismissive hand. "I have the measure of that creature. It thinks it reads my mind but it is the other way around. I revealed a fraction of my power but it has no idea who I truly am. I, on the other hand, know exactly what the Octocalvariae is. I have discerned every one of its deceits and rues. I know why it has given me this clue. It thinks it is sending me to my doom. It thinks the Dromlach is a real being that will devour me. It does not believe I will ever cross the Great Rift or reach Sabassus."

He lent across the table and stared at Mariah. This time the full weight of his gaze was locked on her. "It is wrong."