Mysteries of Time — Marius Smith

Reunited after their separation at Kirkstall Abbey in 1779, William, Larissa, Luke and Cerah set out to investigate the earliest appearance of the Sapphirus Tempus, curious as to why Talamayn told William that it was the last remaining artefact from an alternative timeline when William recently discovered that it was in fact created by a group of Zyarya who'd crashed on the planet Melhandur. The vampires' investigation leads them to a place called Brigetio in the Roman province of Pannonia in the year 375 AD. While pursuing a man in possession of future technology, William inadvertently prevents the death of Emperor Valentinian the First, and all of future history is affected. Captured by a Roman time ship from the future, they're taken to the year 2148 where the Roman Empire extends across thousands of light years, encompassing hundreds of worlds. But the dangers of the ancient Roman world are srill prevalent in the future, where the least crimes mean being sentenced to the arena to either face execution or die as a gladiator. And simply being a vampire is considered a crime against the empire.

Despite the empire's great power, it is overshadowed by a mysterious threat. Contact is being lost with whole constellations at a time, insubstantial wraiths are appearing across the empire, and a rebel faction is in operation right under the Roman's noses with plans to change history to undermine the empire's power in the future. If they succeed while the vampires are still in 2148 they will be erased with the rest of future history. Amid rumours that the empire is being invaded by an even more powerful force, and with no help coming from Temporal Security, the vampires are left to fend for themselves while facing mortal danger on every side.