The Enchantress: The Secrets of the Immortal Nicholas Flamel, Book 6

It's almost the end. Far in the past, the ancient island of Danu Talis is about to fall. In the present, hundreds of fearsome mythological creatures are about to be unleashed on San Francisco. Saving Danu Talis means saving the Elders, who despise the beings they call humani and rule over them with an iron fist. That's where Sophie and Josh have ended up with Virginia Dare and John Dee, and -- can it be? -- their parents are there, too? Better known as Osiris and Isis, they claim to have been grooming the twins for their true calling, their powerful pure gold and silver auras proof of their claim to the throne. But with the help of Virginia Dare, the humani are rising up, and old friends Shakespeare, Joan of Arc, Scathach, and others drop in with an offensive from Hekate's tree kingdom. Sophie and Josh need to think about whose side they're really on -- and on Alcatraz, so do Machiavelli and friends. They've stopped the first wave of monsters from coming ashore, but will they side with old enemies the Flamels and battle hundreds of other fearsome creatures to keep the human race safe? With some fearsome Dark Elders against them, they only have one very foggy night to fight. And without the Codex to restore their immortality, the rapidly aging Flamels will only last that long anyway.