A woman gives birth to her child in a village in Northern England, the cold northern edge of the Roman Empire. As she struggles through a painful labour she begins to scream out a series of words in Latin. A language she has never heard before, much less spoken. One of the family recognises the words for what they are. Only later does it become clear that the women has spoken a prophecy. A prophecy that relates to the death of the Emperor Constantine. A prophecy that if enacted will change the fate of the Roman Empire and all of the future beyond it. Stephen Baxter's new series takes ordinary individuals living at history's tipping points and presents them with a prophecy that challenges everything they believe about their world and prompts them to take action that could change it forever. The fourth volume reveals the nature of the prophecies and reveals a battle that has been fought through the ages.