The Tracker takes the case of a French alchemist who is targeted for his secrets in this mystery set in the gritty streets of fourteenth century London.

After losing his knighthood, Crispin Guest has found a new calling as the Tracker, a private investigator who can locate anything—or anyone. Now famed French alchemist Nicholas Flamel needs Crispin to locate his wife, Perenelle, and his apprentice, Thomas Cornhill. But the case takes a sinister turn when Flamel's apprentice is found murdered. The kidnapper promises that Flamel's wife will be next . . . unless he hands over his precious Philosopher's Stone, a magical object that can turn lead into gold.

Soon, strange, antiquated symbols begin appearing throughout the city. Crispin must decipher their meaning to unearth the kidnappers true motive. Plunged into an underground world where alchemy combines with treacherous politics, Crispin will have to unravel the mystery in order to find his wife and unmask a dangerous mastermind determined to wreak havoc throughout the city.