Sixteen-year-old Gwen, the newest and final member of the secret time-traveling Circle of Twelve, searches through history for the other time-travelers, aided by friend Lesley, James the ghost, Xemerius the gargoyle demon, and Gideon, the Diamond, whose fate seems bound with hers.

The journey begins on a ship at sea in 1766, with a boy named Billy Marvel. After surviving a shipwreck, he finds work in a London theatre. There, his family flourishes for generations as brilliant actors until 1900, when young Leontes Marvel is banished from the stage. Nearly a century later, Joseph Jervis runs away from school and seeks refuge with a reclusive uncle in London. Albert Nightingale's strange, beautiful house, with its mysterious portraits...

Since learning she is the Ruby, the final member of the time-traveling Circle of Twelve, nothing has gone right for Gwen and she holds suspicions about both Count Saint-German and Gideon, but as she uncovers the Circle's secrets she finally learns her own destiny.