The events of the "Book of Eternity" are set in prehistoric Crete, the largest Greek island. Back then, Cronos and the other Titans dominated the globe. Cronos, the son of Uranus and Gaia, was a tyrant who would stop at nothing to keep his hold on power among the Titans. People feared him, but they also respected his power and will.
For millennia, the Titans under Cronos's command dominated the globe. However, the Titanomachy—a catastrophic conflict between the Titans and the Olympians—finally brought an end to their rule. To take their rightful place as rulers of the world from the Titans, Zeus and the Olympians were a new generation of gods.
The Titanomachy was an extensive conflict that was waged on numerous fronts around the globe. The Olympians prevailed after a fierce battle in which the Titans used all their strength. Once the Titans were cast into Tartarus, the underworld, the Olympians took over as rulers of the planet.
That's what everyone supposed, anyway. However, even in defeat, Zeus and the Olympians still respected Cronos's great might. They were aware that Cronos would prove to be an extremely dangerous opponent if he were ever to escape his prison, and so they were resolved to keep him there indefinitely.
This was accomplished when Zeus and the other Olympians resolved to bind Cronos and his influence in a tome they termed the Book of Eternity. According to legend, whomever owned this book would have the ability to manipulate time itself and possess the power of eternity. After Cronos' power was completely encased in the Book of Eternity, its cover was adorned with an Ouroboros bearing the Cronos sign.
Zeus, Poseidon, and Hades pledged to keep the Book of Eternity hidden in the Mortal Realm for the rest of their eternal lives. They took human forms and hid among regular people, adopting new identities and moving frequently to avoid detection. For the sake of humanity and the survival of all forms of life, they were resolved to safeguard the Book of Eternity and the mysteries it contained.
A narrative of strength, terror, and resolve, "The Book of Eternity" tells its story. The Olympians went to great measures in order to permanently imprison the Titans after their defeat in the fight with the gods. It tells a tale about the perils and power of eternity. That tale will be told for generations to come.