While working at pleasant but mundane summer jobs in San Francisco, fifteen-year-old twins, Sophie and Josh, suddenly find themselves caught up in the deadly, centuries-old struggle between rival alchemists, Nicholas Flamel and John Dee, over the possession of an ancient and powerful book holding the secret formulas for alchemy and everlasting life.

For twelve-year-old Emily, the best thing about moving to San Francisco is that it's the home city of her literary idol: Garrison Griswold, book publisher and creator of the online sensation Book Scavenger (a game where books are hidden in cities all over the country and clues to find them are revealed through puzzles).