Sally Lockhart attempts to find the meaning behind her late father's last letter which contained the phrase "the seven blessings" -- a cryptic message that can strike a man dead with fear. Sally is helped by her friends, including Frederick Garland, a photographer, and Jim, a young assistant at the family's shipping firm. The ever twisting mystery involves assassins, opium dens, Chinese gangs, and the Ruby of Agrapur. The priceless ruby is also sought by the ruthless Mrs. Holland, who is willing to kill to get her hands on it.