The corpse of a shabbily dressed young woman has been discovered in the mud flats of the Thames at low tide. Police assume she's a prostitute, but Dr. Watson suspects something more and goes to his old friend Holmes, now retired and at very loose ends.

Benjamin Franklin Gates and Abigail Chase re-team with Riley Poole and, now armed with a stack of long-lost pages from John Wilkes Booth's diary, Ben must follow a clue left there to prove his ancestor's innocence in the assassination of Abraham Lincoln.

The signs of the zodiac hold many mysteries, Some believe that to follow their path is to find good fortune, but others believe that to be guided by the stars will bring nothing but pain, misery and for some, something much worse.