Rachel Wilde comes from a dimension that exists adjacent to ours. The people there have structured their society around daemon collecting: they locate, catch, and repair malfunctioning daemons (creatures out of phase with our world that tempt people to do good or evil). Now Rachel has been given two unusual assignments: 1) find a person who has been trying to break down dimensional barriers, and 2) track down a missing line of gatekeepers, human placeholders for a daemon that was too badly damaged to repair. Authorities of Rachel's world believe the missing gatekeepers are descended from a girl who went missing from West Africa hundreds of years ago, likely sold into slavery. With no leads to go on, Rachel seeks help from Bach, a raving homeless man who happens to be an oracle. Bach does put her in the path of both of her targets—but he also lands her in a life-threatening situation. Somehow, Rachel has to stop the criminal, reunite a gatekeeper with her stolen past, and, above all, survive.