The third book in Piers Anthony's "Incarnations of Immortality" series: With a Tangled Skein. (From the front flap of the hardcover): It seemed to Niobe that Fate and the Devil had conspired against her. And on this world, where science and magic were equally advanced, both Fate and Satan were very real. So were all the Incarnations - Death, Time, Fate, War, and Nature. They were normal people who had been chosen for their positions and given extraordinary powers. Even Satan was supposed to be an Incarnation, though the Prince of Evil opposed all the others, plotting foully to seize the mastery of the world. When the man Niobe loved was shot, she made a desparate and futile appeal to the Incarnations to save him. But Fate cut his thread, and he died. Then Niobe discovered that he had willingly sacirficed himself; she was supposed to have been the target of the bullet, in a devious, long-range plan of the Devil. To gain a chance for revenge against Satan, she accepted the position of Clotho, the youngest of the three Aspects of Fate. Then, while the son she had left with relatives grew to manhood and had a daughter, Niobe struggled to understand and circumvent Satan's plans. But Satan's plots were incredibly complicated and tangled into the Tapestry of Fate. Now the Evil One was laying a trap to ruin Niobe's granddaughter Luna, who threatened his plans. And her son was sent to Hell by a trick of Satan's. Niobe's only chance to defeat Satan and save her son and Luna was to accept a challenge by the Prince of Deceit - a challenge to be decided in Hell and in a maze of Satan's own devising!