From the back cover:

SHE WAS DIFFERENT

The Immortality Treatments had failed. She was destined to grow old, to wither and fade among them -- the wondrously beautiful, gloriously vain, immortals.

After the floods, the rebuilt the earth. Now the Immortals lived in transmutable homes, they traveled the galaxy, they colonized the sea floor. There was no place for her in their sparkling cities. Because she was different -- she would die.

Her refuge was aboard ship, on the Ilium. Her ocean-floor exploration of buried islands yielded treasures the immortals prized. But among the ruins she discovered a dark, enclosed place -- a special room which contained a power the immortals had lost, a power that if she could but learn it, would transform the world forever....